I've been creating a small application that allows a user to convert images to various sizes and formats. I've been struggling on getting a good solid design with this application. I have the application up and running, but it does integrate good Object-Oriented design. Since this is a personal project, I've been wanting to learn more about integrating interfaces, good class inheritance, object composition, and other elements of OO design.
However, I've been struggling to do so. Don't get me wrong, I know about OO design and what it is, I just don't know how to implement good OO design in projects. Of course its easy to look at class Examples that you read in books, or online. Examples may have simple scenarios such as the following.
Interface IPerson has member functions Walk(), Run() . Abstract Class Person uses IPerson Interface. Class Man and Class Female inherit from Abstract Class Person.
but when it comes to Real Projects I struggle to implement good design. I was hoping for some insight. Here is what I currently have.
Interface:
interface IPicture
{
Bitmap ReturnImage(string path, int width, int height);
}
Main Class that Holds Picture Information. This class basically stores information about the image passed, and information about the new values the user wants (i.e. new size, new file location, new pic format, etc.)
public class MyPictures : IPicture
{
//All Private variables below are properties. Property get/set's have been removed
//for the sake of space
private int _NewWidth;
private int _NewHeight;
private string _NewImgName;
private string _NewImgPath;
private string _NewImgFullPath;
private ImageFormat _NewImgFormat;
//Declare variables to hold values that have been determined
private int _OldWidth;
private int _OldHeight;
private string _OldImgName;
private string _OldImgPath;
//Old Image Format is in String format because of certain extension scenarios.
private string _OldImgFormat;
public MyPictures(Image img, string file)
{
ClearProperties();
//...set properties based on passed variables in constructor...
}
public void ClearProperties()
{
_NewWidth = 0;
_NewHeight = 0;
_NewImgName = "";
_NewImgPath = "";
_NewImgFullPath = "";
_NewImgFormat = null;
_OldWidth = 0;
_OldHeight = 0;
_OldImgName = "";
_OldImgPath = "";
_OldImgFormat = null;
}
public override string ToString()
{
return _OldImgPath;
}
public void ImageSave()
{
Bitmap tempBmp = new Bitmap(_OldImgPath);
Bitmap bmp = new Bitmap(tempBmp, _NewWidth, _NewHeight);
bmp.Save(_NewImgPath + #"\" + _NewImgName + "." + _NewImgFormat.ToString().ToLower(), _NewImgFormat);
}
public Bitmap ImageClone()
{
Bitmap bmp = new Bitmap(_OldImgPath);
return bmp;
}
Bitmap IPicture.ReturnImage(string path, int width, int height)
{
return new Bitmap(new Bitmap(path), width, height);
}
}
Main Class; Starting point of application. This definatly needs some work...
public partial class Form1 : Form
{
static bool hasThreadBeenStopped = false;
static bool imageProcessingComplete = false;
static bool imgConstrained = false;
//Default text when user selects 'All' checkbox for new image name
static string newNameDefault = "'Name' + #";
Utility.Validation.Validate valid = new Utility.Validation.Validate();
public Form1()
{
InitializeComponent();
//Populate Combo Box With Possible Image Formats...
//Conditionally show Image Properties...
ImgPropertiesEnabled();
//Set static progress bar properties...
progressBar1.Minimum = 0;
progressBar1.Step = 1;
}
private void Form1_Load(object sender, EventArgs e)
{
lblImgProcessed.Text = "";
lblFile.Text = "";
txtContentFolder.Text = "";
}
//Delegate declarations. Used for multi-thread processing
public delegate void PopulateTextboxDelegate(Label lbl, string text);
public delegate void ThreadWorkDelegate(Label lbl, string text);
public delegate void ImageDisplayDelegate(Image i);
public delegate void ProgressBarDelegate(ProgressBar p, int step, int value);
//Populate textbox fields with image processed, and image path being processed
public void PopulateTextbox(Label lbl, string text)
{
lbl.Text = "";
lbl.Text = text;
}
public void ThreadWork(Label lbl, string text)
{
this.Invoke(new PopulateTextboxDelegate(PopulateTextbox),
new object[] { lbl, text });
}
//Display Currently Processed Image
public void ImageDisplay(Image i)
{
pbMain.Image = null;
pbMain.Image = i;
}
public void ThreadWorkImg(Image i)
{
this.Invoke(new ImageDisplayDelegate(ImageDisplay),
new object[] {i});
}
//Increment Progress Bar
public void ProgressBarDisplay(ProgressBar pg, int max, int value)
{
//Dynamically set the Progress Bar properties
pg.Maximum = max;
pg.Value = value;
}
public void ThreadProgress(ProgressBar p, int max, int value)
{
this.Invoke(new ProgressBarDelegate(ProgressBarDisplay),
new object[] { p, max, value });
}
private void btnStart_Click(object sender, EventArgs e)
{
string IsValidResult = IsValid();
//If string is empty, Utility passed
if (IsValidResult == "")
{
Thread t = new Thread(new ThreadStart(ProcessFiles));
t.Start();
}
else
{
MessageBox.Show(IsValidResult);
}
}
public void ProcessFiles()
{
int count = 0;
ThreadWorkDelegate w = ThreadWork;
ImageDisplayDelegate im = ThreadWorkImg;
ProgressBarDelegate pb = ThreadProgress;
try
{
foreach (MyPictures mp in lstHold.Items)
{
try
{
if (hasThreadBeenStopped == false)
{
//Disable certain controls during process. We will use the generic
//MethodInvoker, which Represents a delegate that can execute any method
//in managed code that is declared void and takes no parameters.
//Using the MethodInvoker is good when simple delegates are needed. Ironically,
//this way of multi-thread delegation was used because the traditional way as used
//by the rest of the delegates in this method, was not working.
btnApply.Invoke(new MethodInvoker(delegate { btnApply.Enabled = false; }));
btnStart.Invoke(new MethodInvoker(delegate { btnStart.Enabled = false; }));
//Call delegate to show current picture being processed
im.BeginInvoke(mp.ImageClone(), null, null);
mp.ImageSave();
//Increment Count; Image has been processed
count++;
//Invoke Img Proceessed Output
w.BeginInvoke(lblImgProcessed, count.ToString() +
" of " + lstHold.Items.Count.ToString() + " processed",
null, null);
//Invoke File Process Output
w.BeginInvoke(lblFile, mp.NewImgPath, null, null);
//Invoke Progressbar output. Delegate is passed The count of images,
//which will be set as the progressbar max value. the 'count' variable is
//passed to determine the current value.
pb.BeginInvoke(progressBar1, lstHold.Items.Count, count, null, null);
}
else //Thread has been called to stop
{
MessageBox.Show("Image Processing Stopped: " + count + "of " +
lstHold.Items.Count + " processed");
//Enable controls after process
btnApply.Invoke(new MethodInvoker(delegate { btnApply.Enabled = true; }));
btnStart.Invoke(new MethodInvoker(delegate { btnStart.Enabled = true; }));
break;
}
}
catch (Exception ex)
{
MessageBox.Show("Error while processing pictures");
break;
}
}
}
catch (Exception ex)
{
MessageBox.Show("Error while attempting to execute pictures: " + ex.ToString());
}
finally
{
//Loop has ended:
//In finally statement, re-enable disabled controls
//Enable certain controls during process
btnApply.Invoke(new MethodInvoker(delegate { btnApply.Enabled = true; }));
btnStart.Invoke(new MethodInvoker(delegate { btnStart.Enabled = true; }));
//Reset class variables
hasThreadBeenStopped = false;
imageProcessingComplete = false;
}
}
private void btnContent_Click(object sender, EventArgs e)
{
string selection = null;
string[] files = null;
lstAll.Items.Clear();
contentBrowser.ShowDialog();
selection = contentBrowser.SelectedPath;
txtContentFolder.Text = selection;
if (selection != "" || selection != null)
{
try
{
files = System.IO.Directory.GetFiles(selection.Trim());
foreach (string file in files)
{
lstAll.Items.Add(file);
}
}
catch (Exception ex)
{
// MessageBox.Show(ex.ToString());
}
}
}
private void btnGo_Click(object sender, EventArgs e)
{
//Grab files from folder based on user input in the textbox.
string selection = txtContentFolder.Text.Trim();
string[] files = null;
lstAll.Items.Clear();
if (valid.IsNull(selection) == false || valid.IsEmpty(selection) == false)
{
try
{
files = System.IO.Directory.GetFiles(selection);
foreach (string file in files)
{
lstAll.Items.Add(file);
}
}
catch (Exception ex)
{
MessageBox.Show("Invalid Directory");
}
}
txtContentFolder.Text = selection;
}
private void btnDestination_Click(object sender, EventArgs e)
{
string selection = null;
destinationBrowser.ShowDialog();
selection = destinationBrowser.SelectedPath;
txtNewImgPath.Text = selection;
}
private void exitToolStripMenuItem_Click(object sender, EventArgs e)
{
this.Close();
}
private void btnStop_Click(object sender, EventArgs e)
{
//Flag variable that the stop button has been called. This variable is checked
//conditionally when looping over each picture.
hasThreadBeenStopped = true;
}
public string IsValid()
{
StringBuilder sb = new StringBuilder("");
if (lstHold.Items.Count <= 0)
{
return "No items exist to process";
}
//Validate that there is a value in each field for every object in lstHold. All the fields will be
//validated. Note: If there is one invalid field, the rest do not need to be considered.
foreach (MyPictures mp in lstHold.Items)
{
if (mp.NewImgName == "")
{
sb.Append(mp.OldImgPath + ", ");
}
else if (mp.NewImgPath == "")
{
sb.Append(mp.OldImgPath + ", ");
}
else if (mp.NewImgFormat == null)
{
sb.Append(mp.OldImgPath + ", ");
}
else if (mp.NewWidth == 0)
{
sb.Append(mp.OldImgPath + ", ");
}
else if (mp.NewHeight == 0)
{
sb.Append(mp.OldImgPath + ", ");
}
}
//If the returned string is empty, the image is valid. The check for the listbox's count
//will return a string immediatly if false. Because of this, we know that the returning
//string at this level will either be empty (validation passed) or filled with image paths
//of images missing required values. If image is not valid, return this concatenated string of image paths
//that are missing values, and insert a prefixed string literal to this list.
if (sb.ToString() != "")
{
sb.Insert(0, "The following images are missing required values: ");
return sb.ToString();
}
else //String is empty and has passed validation
{
return sb.ToString();
}
}
private void btnMoveOne_Click(object sender, EventArgs e)
{
//Loop through All strings in the lstAll list box. Then use each picture path to convert
//each picture into their own class
foreach (string file in lstAll.SelectedItems)
{
//isImgExistFlag is a flag indicating wheter the image coming from lstAll already exists
//in lstHold. By default, the variable is false. It is set to true if an image does exist
//This variable must be re-created within the scope of the main foreach loop to ensure a proper
//reset of the variable for each image comparison.
bool isImgExistFlag = false;
try
{
Image img;
img = Image.FromFile(file);
MyPictures mp = new MyPictures(img,file);
//If lstHold contains no items, add the item with no validation check.
if (lstHold.Items.Count == 0)
{
lstHold.Items.Add(mp);
}
else
{
//Run through each object in the lstHold to determine if the newly created object
//already exists in list box lstHold.
for (int i = 0; i < lstHold.Items.Count; i++)
{
MyPictures p = (MyPictures)lstHold.Items[i];
//Unique objects will be identified by their Original Image Path, because
//this value will be unique
if (p.OldImgPath == mp.OldImgPath)
{
isImgExistFlag = true;
}
}
//If isImgExistFlag is false, the current Image object doesnt currently exist
//in list box. Therefore, add it to the list.
if (isImgExistFlag == false)
{
lstHold.Items.Add(mp);
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
private void btnMoveAll_Click(object sender, EventArgs e)
{
//This event has the same functionality as btnMoveOne_Click, except the main foreach loop
//is based on all of lstAll's items, rather than just the selected items.
foreach (string file in lstAll.Items)
{
bool isImgExistFlag = false;
try
{
Image img;
img = Image.FromFile(file);
MyPictures mp = new MyPictures(img, file);
if (lstHold.Items.Count == 0)
{
lstHold.Items.Add(mp);
}
else
{
for (int i = 0; i < lstHold.Items.Count; i++)
{
MyPictures p = (MyPictures)lstHold.Items[i];
if (p.OldImgPath == mp.OldImgPath)
{
isImgExistFlag = true;
}
}
if (isImgExistFlag == false)
{
lstHold.Items.Add(mp);
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
private void btnRemoveOne_Click(object sender, EventArgs e)
{
/*
Create a seperate List to populate:
This is necessary because if you explicitly remove an item from the listbox
you will get the following error:
"List that this enumerator is bound to has been modified. An enumerator can
only be used if the list does not change."
*/
//This variable will keep track of the first index processed.
int first_index = 0;
int count = 0;
List<MyPictures> TempMp = new List<MyPictures>();
if (lstHold.Items.Count >= 1)
{
try
{
foreach (MyPictures mp in lstHold.SelectedItems)
{
if (count == 0)
{
first_index = lstHold.SelectedIndex;
}
//Add objects to be removed
TempMp.Add(mp);
}
foreach (MyPictures mp2 in TempMp)
{
lstHold.Items.Remove(mp2);
}
}
catch (Exception ex)
{
//Hide Error: MessageBox.Show(ex.ToString());
}
//Select new item in list if possible, as long as there is a item in the list
if (lstHold.Items.Count >= 1)
{
//If the first_index variable = the amount of items in the list, the new selected index
//should be the first index -1. This is because the variable first_index would be the
//index of the now deleted item in the list. Therefore we must subtract the variable by 1
//before assigning it to the selected value. Otherwise, we'll be assigning a selected index that
//no longer exists.
//There is also a check to make sure there is more than one item in the list. Otherwise, we could
//potentially assign a selected index of -1.
if (first_index == lstHold.Items.Count && lstHold.Items.Count != 1)
{
lstHold.SelectedIndex = first_index - 1;
}
else if (lstHold.Items.Count == 1)
{
lstHold.SelectedIndex = 0;
}
else
{
lstHold.SelectedIndex = first_index;
}
}
else
{
ClearTextBoxes();
}
}
}
private void btnRemoveAll_Click(object sender, EventArgs e)
{
lstHold.Items.Clear();
ClearTextBoxes();
ImgPropertiesEnabled();
}
private void lstHold_SelectedIndexChanged(object sender, EventArgs e)
{
//This prevents trying to access a negative index. This can happen when a item is removed.
if (lstHold.SelectedIndex >= 0)
{
try
{
MyPictures mp = (MyPictures)lstHold.Items[lstHold.SelectedIndex];
txtOldName.Text = mp.OldImgName;
txtOldImgPath.Text = mp.OldImgPath;
txtOldImgFormat.Text = mp.OldImgFormat.ToString();
txtOldWidth.Text = mp.OldWidth.ToString();
txtOldHeight.Text = mp.OldHeight.ToString();
txtNewName.Text = mp.NewImgName;
cbFormat.SelectedItem = mp.NewImgFormat;
txtNewWidth.Text = mp.NewWidth.ToString();
txtNewHeight.Text = mp.NewHeight.ToString();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
//Call function to determine which controls should be enabled/disabled
ImgPropertiesEnabled();
}
private void btnApply_Click(object sender, EventArgs e)
{
//Reset color. It could be grey depending on if user changed default name.
txtNewName.ForeColor = Color.Black;
if (lstHold.SelectedIndex == -1)
{
MessageBox.Show("Picture not selected. Select picture to apply properties to.");
}
else if (lstHold.SelectedIndex >= 0)
{
MyPictures mp = (MyPictures)lstHold.Items[lstHold.SelectedIndex];
//User wants to apply a generated name to all pictures within the list
if (chkNewPicName.Checked == true)
{
int count = 0;
foreach (MyPictures pic in lstHold.Items)
{
pic.NewImgName = txtNewName.Text + count.ToString();
++count;
}
txtNewName.Text = mp.NewImgName;
}
//User wants to apply a custom name to this picture only
else
{
mp.NewImgName = txtNewName.Text;
}
//User wants to apply this path to all pictures within the list
if (chkNewPicPath.Checked == true)
{
foreach (MyPictures pic in lstHold.Items)
{
pic.NewImgPath = txtNewImgPath.Text;
}
txtNewImgPath.Text = mp.NewImgPath;
}
//User wants to apply this path to this picture only
else
{
mp.NewImgPath = txtNewImgPath.Text;
}
//User wants to apply this image format to all pictures within the list
if (chkNewPicFormat.Checked == true)
{
foreach (MyPictures pic in lstHold.Items)
{
pic.NewImgFormat = (ImageFormat)cbFormat.SelectedItem;
}
}
//User wants to apply this image format to this picture only
else
{
mp.NewImgFormat = (ImageFormat)cbFormat.SelectedItem;
}
//User wants to apply this size to all pictures
if (chkNewSize.Checked == true)
{
foreach (MyPictures pic in lstHold.Items)
{
pic.NewWidth = Convert.ToInt32(txtNewWidth.Text);
pic.NewHeight = Convert.ToInt32(txtNewHeight.Text);
}
txtNewWidth.Text = mp.NewWidth.ToString();
txtNewHeight.Text = mp.NewHeight.ToString();
}
//User wants to apply this size to this picture only
else
{
mp.NewWidth = Convert.ToInt32(txtNewWidth.Text);
mp.NewHeight = Convert.ToInt32(txtNewHeight.Text);
}
mp.NewImgName = txtNewName.Text;
mp.NewImgFormat = (ImageFormat)cbFormat.SelectedItem;
mp.NewWidth = Convert.ToInt32(txtNewWidth.Text);
mp.NewHeight = Convert.ToInt32(txtNewHeight.Text);
}
}
private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
if (chkSelectAll.Checked)
{
chkNewPicName.Checked = true;
chkNewPicPath.Checked = true;
chkNewPicFormat.Checked = true;
chkNewSize.Checked = true;
}
else
{
chkNewPicName.Checked = false;
chkNewPicPath.Checked = false;
chkNewPicFormat.Checked = false;
chkNewSize.Checked = false;
}
}
private void previewToolStripMenuItem_Click(object sender, EventArgs e)
{
MessageBox.Show("hi there!");
}
private void btnPreview_Click(object sender, EventArgs e)
{
try
{
if (lstHold.Items.Count <= 0)
{
MessageBox.Show("No pictures are available to preview");
}
else if (lstHold.SelectedItem == null)
{
MessageBox.Show("No picture is selected to preview");
}
else
{
MyPictures mp = (MyPictures)lstHold.SelectedItem;
//Bitmap bmp = new Bitmap(mp.OldImgPath);
Form2 frm = new Form2(mp);
frm.Show();
}
}
catch (Exception ex)
{
MessageBox.Show("An Error has occured:\n " + ex.ToString());
}
}
public void ImgPropertiesEnabled()
{
//Enable Image properties when an image is selected
if (lstHold.SelectedIndex >= 0)
{
gbCheckAll.Enabled = true;
gbImgProperties.Enabled = true;
}
else
{
//Disable Image properties when an image is not selected
gbCheckAll.Enabled = false;
gbImgProperties.Enabled = false;
}
//Preview buttons enablement will depend on the same conditions
btnPreview.Enabled = gbImgProperties.Enabled;
}
public void ClearTextBoxes()
{
txtNewImgPath.Text = "";
txtNewName.Text = "";
txtNewHeight.Text = Convert.ToString(0);
txtNewWidth.Text = Convert.ToString(0);
cbFormat.SelectedItem = null;
chkSelectAll.Checked = false;
}
}
Having scanned through the code, yes it is eleborate... maybe a little to much ;)
One thing that i noticed was your naming conventions. Even though it does not change anything in runtime it does make an API/code-maintenance easier.
So, instead of having an IPicture, i would make it something like `IResizableImage´ (reading your spec, thats what it is. Not just a picture, but a resizable one)
Instead of ´ReturnImage()´ i would use something like ´Scale()´. 'ImageSave()' to 'Save()'
Your code will start to read (Which added symantical information by naming convention)
IResizableImage myImg = new ResizableImage( orignalBitmap );
Image rescaledImg = myImg.Scale( "new path", 320,240 );
resccaledImg.Save();
instead of:
IPicture myImg = new MyPictures();
Image rescaled = myImg.ReturnImage( "newpath", 320, 240 );
rescaledImg.ImageSave();
So, Generally classes are nouns, methods are verbs, adjetives are properties/fields. Try to minimize duplication or redancy. "ImageSave" is a method on your Image. Isn't "Image.Save()" clearer than "Image.ImageSave()"?
Just some of my thoughts;
In coding guidelines there is no absolute right or wrong.
Think of being another person when USING the API versus WRITING the API. Jump out of the box of "i know what it does" and imagine being a user never having seen this API before. Does it feel natural and easy accesible?
Hope this helps,
Here are some improvements for you code and design. This tips are not all OO related but you should be aware that good design is not just OO design.
1.Avoid commenting what is obvious.
//Declare variables to hold values that have been determined
private int _OldWidth;
This comment is superfluous because any programmers will understand that is a declaration.
2.Avoid giving wrong name. For example the class "MyPictures" is not really correct because:
Is holds just one picture, while the name suggests many pictures.
It contains "My" which, in my opinion is not correct since if I read your code is not my class. It is yours ;)
3.Avoid concatenating strings. Use string.Format or, for paths, Path.Combine
bmp.Save(_NewImgPath + #"\" + _NewImgName + "." + _NewImgFormat.ToString().ToLower(), _NewImgFormat);
4.Keep methods short. It is hard to keep all methods to 5 lines of code but 30 lines (if my count is correct - without comments and empty lines) for ProcessFiles is a little bit too much.
5.Don't use design elements just because you want to have them. I see no reason to use the interface in your code. In your case it just increases the complexity of your code. Even more, you haven't used it(!!!). You just implemented it and that's all. Use interfaces when you have multiple types that share common functionality (the ones in interface) and you want to treat them all similar without being aware of the actual implementation.
interface IImage
{
void DrawLine(Point startPoint, Point endPoint);
}
class MonochromeImage:IImage
{
void DrawLine(Point startPoint, Point endPoint)
{
//Draw a monochrome line on images with one channel
}
}
class ColorImage:IImage
{
void DrawLine(Point startPoint, Point endPoint)
{
//Draw a red line on images with three channels
}
}
...
void DrawLineOnImage()
{
List<IImage> images = new List<IImage>();
images.Add(new ColorImage());
images.Add(new MonochromeImage());
//I am not aware of what kind of images actually have
//all it matters is to have a draw line method
foreach(IImage image in images)
{
image.DrawLine(p1,p2)
}
}
6.As others already mentioned, try to separate the presentation (graphical user interface - GUI) from the logic. Make it in such a way that you can replace the GUI without changing logic code.
7.Make single responsibility functions. btnMoveOne_Click has more than one responsibility: it checks if file exists and it handles elements on user interface.
8.You image class is coupled to the file system. What happens if I want to store images created in memory? What is the path then? Here is where you can improve the design of the class. Make it in such a way it doesn't matter if files are from disk (HINT: in a FileStream) or from memory (HINT: in a MemoryStream) or any other place.
That's all for now. Hope this information will help you.
To achieve good design you need to apply TDD (Test Driven Design).
You will soon find then testability requires separating the project to layers, such as presentation and business logic.
Start covering your project with tests, and you won't believe how fast you will find design inconsistences with it.
Things will just stand up and scream: "No way you will test me!"
The worst anemy nere is the code buried in the WinForms.
What you can do is making a view "humble". http://codebetter.com/blogs/jeremy.miller/archive/2007/05/23/build-your-own-cab-part-2-the-humble-dialog-box.aspx
As for the project samples, you have to look at architectural patterns, not the OOP samples.
The keywords you will be lookign for are MVC, MVP, MVVM.
Well, here's what I'd do. It's probably different than what many people would do, but I think it's a pretty good, flexible design.
public abstract class AbstractConverter : IImageHandler
{
public AbstractConverter(IImageHandler nextHandler)
{
output = nextHandler;
}
public void HandleImage(Bitmap b)
{
var outBitmap = Convert(b);
output.HandleImage(outBitmap);
}
protected abstract Bitmap Convert(Bitmap input);
private IImageHandler output;
}
public interface IImageHandler
{
void HandleImage(Bitmap b);
}
Now, the rest of your app is:
Creating implementations of AbstractConverter to handle the individual transformations you want
Creating something that can build and wire converters together
Getting the initial Bitmap, and writing the final result out.
Related
I'm using C# Windows Forms Application to create a simple application. I've used a listBox to read and display a text file (10 lines). How to specify the First, Last, Previous and Next line in the listBox by pressing a proper button? Any help will be appreciated. Thank you.
[enter image description here][1]
How to specify the First, Last, Previous and Next line in the listBox by pressing a proper button?
Note: This answer assumes you want only show one line at a time, either it be the first line, next, previous and or last line in the text file.
Let's first go over your current approach. The routine button6_Click is only trying to load a file, read the line and if the line/string is not null then add this string to listBox1; this is doing this for every string in that file. The usage of OpenFileDialog and StreamReader implement IDisposable, you should wrap these in a using block to ensure objects are properly disposed of as well.
Your current approach is more than likely not what you need as you don't want to load everything up at once, only when needed. With this in mind, you would need to keep some sort of collection of these lines from the file; there's more than a few ways, but I will focus on just one way.
First, create a new class as per below:
public class NavigateFile
{
// Stores the file lines collection
public IEnumerable<string> CurrentFileLines { get; private set; }
// Tracks the current line index
public int CurrentFileLineIndex { get; private set; } = 0;
// Tracks the next line index
public int NextFileLineIndex { get; private set; } = 1;
// Tracks the previous line index
public int PreviousFileLineIndex { get; private set; } = -1;
// Tracks the last line index
public int LastFileLineIndex { get; private set; } = 0;
// Routine to load the file
public void LoadFile()
{
using (OpenFileDialog ofd = new OpenFileDialog())
if (ofd.ShowDialog() == DialogResult.OK)
CurrentFileLines = File.ReadLines(ofd.FileName).Where(line => !string.IsNullOrEmpty(line));
CurrentFileLineIndex = 0;
NextFileLineIndex = 1;
PreviousFileLineIndex = -1;
LastFileLineIndex = CurrentFileLines.Count();
}
// Routine return the first line in the file
public string GoToFirstLine()
{
CurrentFileLineIndex = 0;
return CurrentFileLines.ToList()[CurrentFileLineIndex];
}
// Routine return the next line in the file if we can
public string GoToNextLine()
{
if((CurrentFileLineIndex + 1) <= CurrentFileLines.Count() - 1)
{
CurrentFileLineIndex++;
return CurrentFileLines.ToList()[CurrentFileLineIndex];
}
return CurrentFileLines.ToList()[CurrentFileLineIndex];
}
// Routine return the previous line in the file if we can
public string GoToPreviousLine()
{
if ((CurrentFileLineIndex - 1) >= 0 && (CurrentFileLineIndex - 1) <= CurrentFileLines.Count())
{
CurrentFileLineIndex--;
return CurrentFileLines.ToList()[CurrentFileLineIndex];
}
return CurrentFileLines.ToList()[CurrentFileLineIndex];
}
// Routine return the last line in the file
public string GoToLastLine()
{
CurrentFileLineIndex = CurrentFileLines.Count() - 1;
return CurrentFileLines.Last();
}
}
Next you could use this simply by calling a few functions to return what you would need. Put below logic in your specific buttons to handle what you would need to.
// put this in your class where you will be using the new class
private NavigateFile NavigateFile { get; set; } = new NavigateFile();
// Load a file
listBox1.Items.Clear();
NavigateFile.LoadFile();
listBox1.Items.Add(NavigateFile.GoToFirstLine());
// Go to first line
listBox1.Items.Clear();
listBox1.Items.Add(NavigateFile.GoToFirstLine());
// Go to next line
listBox1.Items.Clear();
listBox1.Items.Add(NavigateFile.GoToNextLine());
// Go to previous line
listBox1.Items.Clear();
listBox1.Items.Add(NavigateFile.GoToPreviousLine());
// Go to last line in the file
listBox1.Items.Clear();
listBox1.Items.Add(NavigateFile.GoToLastLine());
If you should need to lookup an item, you can build a Linq query against CurrentFileLines in the NavigateFile class and pull what you would need, it may be helpful if needed somewhere.
Note:
I was clearing out the listBox1.Items every time I did something, you don't have to, but I did. Also keep in mind, make sure you have a file loaded before calling any of these functions and or edit them to make sure you have data. If there is something you don't understand, please let me know and I can help.
I ~think~ you're asking how to change the selected item in the listbox by pressing the buttons?
If so, something like:
OpenFileDialog openFile = new OpenFileDialog();
private void btnLoadFile_Click(object sender, EventArgs e)
{
if (openFile.ShowDialog() == DialogResult.OK )
{
try
{
List<String> lines = new List<String>(System.IO.File.ReadAllLines(openFile.FileName));
lines.RemoveAll(l => l.Trim().Length == 0);
if (lines.Count > 0)
{
listBox1.Items.Clear();
listBox1.Items.AddRange(lines.ToArray());
}
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString(), "Error Loading File");
}
}
}
private void btnFirst_Click(object sender, EventArgs e)
{
if (listBox1.Items.Count > 0)
{
listBox1.SelectedIndex = 0;
}
}
private void btnLast_Click(object sender, EventArgs e)
{
if (listBox1.Items.Count > 0)
{
listBox1.SelectedIndex = (listBox1.Items.Count - 1);
}
}
private void btnPrevious_Click(object sender, EventArgs e)
{
if (listBox1.Items.Count > 0)
{
listBox1.SelectedIndex = (listBox1.SelectedIndex > 0) ? (listBox1.SelectedIndex - 1) : 0;
}
}
private void btnNext_Click(object sender, EventArgs e)
{
if (listBox1.Items.Count > 0)
{
listBox1.SelectedIndex = (listBox1.SelectedIndex < (listBox1.Items.Count - 1)) ? (listBox1.SelectedIndex + 1) : (listBox1.Items.Count - 1);
}
}
Note that if no item is currently selected, then pressing previous or next will select the first item in the listbox.
I currently have a dynamic number of smaller panels being added to large panel. I have a separate form that returns a list of workspaceID's.
Each WorkSpaceControl has a global variable get,set that stores the workspaceID and I don't see a way to access these in my current scope.
WorkSpaceControl wsp = wch.GenerateWorkspaceControl(items, space.Id, space.Name, point);
workSpaceList.Add(wsp);
k++;
col++;
foreach (WorkSpaceControl p in workSpaceList)
{
/// allow something to be dragged onto the space and catches something
p.AllowDrop = true;
p.DragEnter += formDragEnter;
p.DragDrop += formDragDrop;
// Event handler for draggin picturebox
p.ItemIcon.MouseDown += new MouseEventHandler(moveIcon_MouseDown);
/// event handler for updating icons and quantity based on selected item
p.Child_ItemIndexChanged += c_SelectedIndexChanged;
PanelTest.Controls.Add(p);
}
private void btnFindByCustom_Click(object sender, EventArgs e)
{
ih_FindByCustom findCust = new ih_FindByCustom();
var result = findCust.ShowDialog();
if (result == DialogResult.OK)
{
List<int> workspaceidstohighlight = findCust.workspaceIdsToHighlight;
//highlihgt the panels in the workspaceidtohighlight
Panel p = (Panel)((Button)sender).Parent.Parent;
}
}
I need access to all the workspaceControl's that are on panel p.
I solved it but it's pretty ugly
private void btnFindByCustom_Click(object sender, EventArgs e)
{
ih_FindByCustom findCust = new ih_FindByCustom();
var result = findCust.ShowDialog();
if(result == DialogResult.OK)
{
List<int> workspaceidstohighlight = findCust.workspaceIdsToHighlight;
//highlihgt the panels in the workspaceidtohighlight
if (workspaceidstohighlight.Count != 0)
{
foreach (WorkSpaceControl list in workSpaceList)
{
foreach (int idtohighlight in workspaceidstohighlight)
{
if (list.WorkspaceID == idtohighlight)
{
list.backPanel.BackColor = Color.Yellow;
}
}
}
}
}
}
I wish to not make workSpaceList a global variable but i cannot see any other way.
Does anyone have a "cleaner" way of doing this? I saw somewhere that using linq and creating a join would be a possible solution that I am going to look into.
Good day lads!
I've got a question.
I think I'll be saving loads of text if you would see my form, so here we go!
Form:
private void Form1_Load(object sender, EventArgs e)
{
/*
Held h1 = new Held("Tank", Lanes.Top);
Held h2 = new Held("ADC", Lanes.Bot);
Held h3 = new Held("Support", Lanes.Bot);
listBox1.Items.Add(h1);
listBox1.Items.Add(h2);
listBox1.Items.Add(h3);
*/
//Data koppelen
cbRol.DataSource = Enum.GetValues(typeof(Lanes));
}
private void btnAanmaken_Click(object sender, EventArgs e)
{
int getal;
if (CheckEmptyFields())
{
MessageBox.Show("Vul alle velden in!");
}
else
{
if (CheckMovementSpeedIsInt(out getal))
{
string naamHero = tbNaamHero.Text;
Lanes lane = ???
int mSpeedHero = getal;
Held nieuwHeld = new Held(naamHero, lane, getal);
}
}
}
private bool CheckMovementSpeedIsInt(out int getal)
{
return Int32.TryParse(tbMoveSpeed.Text, out getal);
}
private bool CheckEmptyFields()
{
return tbNaamHero.Text == null || tbMoveSpeed.Text == null || cbRol.SelectedItem == null;
}
Held:
class Held
{
private string Naam;
private Lanes Lane;
int MSpeed;
public Held(string aNaam, Lanes aLane, int aMSpeed)
{
this.Naam = aNaam;
this.Lane = aLane;
this.MSpeed = aMSpeed;
}
public override string ToString()
{
return this.Naam + " " + this.Lane.ToString();
}
}
}
Lanes:
enum Lanes
{
Top,
Mid,
Bot,
Jungle
}
Alright! So as you can see I have combined the enum with the ComboBox. I'd like to put the selected value (when the user has pressed the button "Aanmaken/Create") in the instance.
How am I able to convert the object (from ComboBox) to a type (Lanes)?
If I haven't clarified enough, just give me a heads up!
PS: The "???" in the code is the place where I'm not sure what to put since that's the question hehe.
Just use the following:
Lanes lane = (Lanes)cbRol.SelectedIndex;
This works due to enum is typeof int, so your Top is actually 0, and so on...
You can parse your Enum.Parse
Lanes lange = (Lanes) Enum.Parse(typeof(Lanes), cbRol.SelectedItem.ToString(), true);
This also works for index
Lanes lange = (Lanes) Enum.Parse(typeof(Lanes), cbRol.SelectedIndex.ToString(), true);
Problem solved.
The original "private void buttonSave_Click" was changed to:
private void buttonSave_Click(object sender, EventArgs e)
{
if (MusicCollection.FormMain.PublicVars.AlbumList.Count != 100)
{
MusicCollection.FormMain.PublicVars.AlbumList.Add(new Album(NameTextBox.Text));
MessageBox.Show("New Album added: " + NameTextBox.Text);
formMain.ListAlbums(formMain.AlbumsListBox.Items);
this.Close();
}
else
{
MessageBox.Show("No room for new album.");
this.Close();
}
}
Original Post:
I'm new to using C#, so appologies for any seemly obvious mistakes or terrible coding.
I'm trying to create a new Album object (that gets its Name from NameTextBox.Text on Form FormAlbumAC) and add it to List AlbumList when the user clicks the save button on FormAlbumAC. Then I want to list all of AlbumList in a ListBox on Form FormMain.
When I run the program and click the save button, I'm getting the error "ArgumentOutOfRangeException was unhandled, Index was out of range" at the line:
if (MusicCollection.FormMain.PublicVars.AlbumList[i] == null)
// line 8 on my excerpt from Form FormAblumAC
I'm not sure what I'm doing wrong. Any help would be much appreciated, thank you.
Form FormMain:
public const int MAX_ALBUMS = 100;
public int totalAlbums = 0;
public FormMain()
{
InitializeComponent();
}
public static class PublicVars
{
public static List<Album> AlbumList { get; set; }
static PublicVars()
{
AlbumList = new List<Album>(MAX_ALBUMS);
}
}
public ListBox AlbumListBox
{
get
{
return AlbumListBox;
}
}
public void ListAlbums(IList list)
{
list.Clear();
foreach (var album in PublicVars.AlbumList)
{
if (album == null)
continue;
list.Add(album.Name);
}
}
Form FormAlbumAC:
private FormMain formMain;
private void buttonSave_Click(object sender, EventArgs e)
{
int index = -1;
for (int i = 0; i < MusicCollection.FormMain.MAX_ALBUMS; ++i)
{
if (MusicCollection.FormMain.PublicVars.AlbumList[i] == null)
{
index = i;
break;
}
}
if (index != -1)
{
MusicCollection.FormMain.PublicVars.AlbumList[index] = new Album(NameTextBox.Text);
++formMain.totalAlbums;
MessageBox.Show("New Album added: " + NameTextBox.Text);
formMain.ListAlbums(formMain.AlbumsListBox.Items);
this.Close();
}
else
{
MessageBox.Show("No room for new album.");
this.Close();
}
}
Your problem (from your comments) is that your for loop's condition is incorrect. Your for loop is this:
for (int i = 0; i < MusicCollection.FormMain.MAX_ALBUMS; ++i)
There is one problem and one potential problem here. First, when this code is actually run, it's really running:
for (int i = 0; i < 100; ++i)
because MusicCollection.FormMain.MAX_ALBUMS is declared as 100. This causes an error when the length of MusicCollection.FormMain.PublicVars.AlbumList is less than 100, because you're trying to grab an index that doesn't exist.
Instead, you need to iterate from i=0 to the length of ....PublicVars.AlbumList-1, or, preferably, for(int i = 0; i < ....PublicVars.AlbumList.Count; i++).
The second potential problem is that you are potentially skipping index 0. Arrays start at index zero and continue to index length-1. As such, you probably want i++, not ++i. Depends on your implementation, though.
I have an xml file which was built up from blocks like this:
<BasicOptions id="OwnCrypt">
<Font>Angsana New</Font>
<FontColor>Aquamarine</FontColor>
<FontSize>12</FontSize>
<FontStyle>Normál</FontStyle>
<BackgroundImage>Cryptonite\System\Resources\Media\Pics\grumpy.jpg</BackgroundImage>
<ImageResolution>1280 X 1024</ImageResolution>
<FormSize>1280 X 1024</FormSize>
<FormPosition>CenterParent</FormPosition>
<Opacity>70</Opacity>
</BasicOptions>
I made six of these blocks in a root element( named Options). I have some problem with the
<FormSize> node, because from the options form it can get empty value( which means I don't change it's resolution), and then I would like to set the <FormSize> node's value to the basic resolutions of the forms.
Here is the updater button event( if it helps anything):
private void button1_Click(object sender, EventArgs e)
{
boxes[0] = checkBox1;
boxes[1] = checkBox2;
boxes[2] = checkBox3;
boxes[3] = checkBox4;
boxes[4] = checkBox5;
boxes[5] = checkBox6;
ArrayList al = new ArrayList();
ArrayList bl = new ArrayList();
foreach (CheckBox cb in boxes)
{
if (cb.Checked)
al.Add(cb.Text);
}
if(comboBox1.Text=="")//Betűtípus
{
bl.Add("Times New Roman");
}
else
bl.Add(comboBox1.Text);
if (comboBox2.Text == "")//Betűszín
{
bl.Add("Fekete");
}
else
bl.Add(comboBox2.Text);
bl.Add(numericUpDown1.Value.ToString());//Betűméret
if (comboBox3.Text == "")//Betűstílus
{
bl.Add("Normál");
}
else
bl.Add(comboBox3.Text);
if (comboBox4.Text == "")//háttérkép
{
bl.Add(#"Cryptonite\System\Resources\Media\Pics\grumpy.jpg");
}
else
bl.Add(comboBox4.Text);
if (comboBox5.Text == "")//háttérkép felbont
{
Xml.resRequest(al);
}
else
bl.Add(comboBox5.Text);
if (comboBox6.Text == "")//felbontás
{
Xml.resRequest(al);
}
else
bl.Add(comboBox6.Text);
if (comboBox7.Text == "")
{
bl.Add("WindowsDefault");
}
else
bl.Add(comboBox7.Text);
bl.Add(numericUpDown2.Value.ToString());
Xml.Writer(al, bl);
al.Clear();
bl.Clear();
}
It has an order to get the values and give to the updater method, but if anybody has a better idea, that makes me very happy. :)
I would use a DTO object to store the values and use one of the built in serializers to form the xml. http://msdn.microsoft.com/en-us/library/system.xml.serialization.xmlserializer.aspx
The DTO class would have properties that you could use to detect if the value needs to be set to the default.
public class Foo {
private string _bar;
public string Bar
{
get { return String.IsNullOrEmpty(_bar) ? _bar = "default value" : _bar; }
set { _bar = value; }
}
}
Rather then populating the ArrayList, populate the DTO.