Develop Reference

C# paint program won't create any lines on the screen since I tried to draw using a bitmap

Here is my source code. I can't seem to get the bitmap to show the lines drawn on the panel when I move the mouse with the button pressed. Frustrated and looking for someone to help me finish the code so I can complete the app for my 9-yo daughter. Thank you in advance...
namespace TV_PAINT
{
public partial class ALANA_PAINT : Form
{
Graphics g;
Pen p = new Pen(Color.Black, 7);
Point sp = new Point(0, 0);
Point ep = new Point(0, 0);
int m = 0;
Bitmap BP;
public ALANA_PAINT()
{
InitializeComponent();
tb1.Text = p.Width.ToString();
BP = new Bitmap(pnl1.ClientSize.Width, pnl1.ClientSize.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
}
private void closeButton_Click(object sender, EventArgs e)
{
pnl1.Dispose();
p.Dispose();
this.Close();
}
private void clearButton_Click(object sender, EventArgs e)
{
//pnl1.Invalidate();
p.Color = System.Drawing.Color.Black;
p.Width = 7;
tb1.Text = p.Width.ToString();
//pnl1.Invalidate();
}
private void pnl1_MouseDown(object sender, MouseEventArgs e)
{
sp = e.Location;
if (e.Button == MouseButtons.Left)
m = 1;
if (e.Button == MouseButtons.Right)
m = 1;
}
private void pnl1_MouseMove(object sender, MouseEventArgs e)
{
if (m == 1)
{
ep = e.Location;
//g = pnl1.CreateGraphics();
Graphics g = Graphics.FromImage(BP);
g.DrawLine(p, sp, ep);
}
sp = ep;
}
private void pnl1_MouseUp(object sender, MouseEventArgs e)
{
m = 0;
}

BP is just a variable in the form. As I can see, it is not displayed anywhere in your form. Why do you need a bitmap for it.
You can do something like this, just get the graphics of your form, and draw using that graphic. https://msdn.microsoft.com/en-us/library/ztxk24yx(v=vs.110).aspx
Noted: you need to do it on PaintEvent of the form, otherwise your drawing will be removed after the next repaint, so you need some variables to store all of your lines, then draw all of them in the paint event.
System.Drawing.SolidBrush myBrush = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
System.Drawing.Graphics formGraphics;
formGraphics = this.CreateGraphics();
formGraphics.FillRectangle(myBrush, new Rectangle(0, 0, 200, 300));
myBrush.Dispose();
formGraphics.Dispose();
Updated:
If you want to save your change to a bitmap. You can use Form.DrawToBitmap to save your drawing in the form to a bitmap, then call bitmap.Save() to a file in directory.

How to draw an image in TabPage above nested Buttons

How to draw image on tabPage overlapping buttons
Black circles(DrawImage on tabPage8_Paint) should be above the buttons:
http://rghost.ru/6sVBl8mkh/image.png
It must be so:
http://rghost.ru/6BgDM77pq/image.png
My code
public SibModem() {
InitializeComponent();
tabPage8.Paint += new PaintEventHandler(tabPage8_Paint);
gettime();
this.SizeChanged += new EventHandler(this.SibModem_Resize);
}
protected void tabPage8_Paint(object sender, PaintEventArgs e) {
GraphicsUnit units = GraphicsUnit.Pixel;
base.OnPaint(e);
Graphics g = e.Graphics;
g.DrawImage(bg, 0, 0);
Rectangle srcRect = new Rectangle(offsetant, 0, w, h);
g.DrawImage(anten, x, y, srcRect, units);
Rectangle ussdwaitRect = new Rectangle(offsetussd, 0, 64, 64);
g.DrawImage(ussdwait, usx, usy, ussdwaitRect, units);
}

You can't draw above nested controls, so you need to draw parts of the image onto those Buttons.
So combine drawing onto the tabpage and drawing onto the buttons you need to adorn!
Here is a simple example using only one image:
A few class level variables:
Point iLoc = Point.Empty;
Image img = null;
List<Button> overlaidButtons = new List<Button>();
Prepare the image, its position and a list of possibly overlaid buttons:
public Form1()
{
InitializeComponent();
string imgN = #"d:\scrape\gears\gear_12x4hand.png";
img = Image.FromFile(imgN);
iLoc = new Point(100, 100);
overlaidButtons.AddRange(new []{button10,button11,button12,button13 });
// each button calls the same paint event
foreach (Button btn in overlaidButtons) btn.Paint += btn_Paint;
}
The common Paint event. We calculate the relative position of the image..
void btn_Paint(object sender, PaintEventArgs e)
{
Button btn = sender as Button;
e.Graphics.DrawImage(img, new Point(iLoc.X - btn.Left, iLoc.Y - btn.Top));
}
Note that if the Buttons are nested deeper you need to adapt the calculation to include all levels of nesting!
The TabPage Paint event:
private void tabPage5_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawImage(img, iLoc);
}

Try BringToFront method, it brings the control to the front of the z-order.
See this reference on MSDN: https://msdn.microsoft.com/en-us/library/system.windows.forms.control.bringtofront(v=vs.110).aspx

Can I draw shapes within buttons?

I've been reading stackoverflow for a while now just to learn, and I've come across a situation where I can finally ask a question. I'm making a Simon Says type memory game, where I flash shapes at the user, and the user has to click a button in the same order the shapes were shown to them. I want to draw the shape that I'm drawing on the screen within the button that they are clicking because it's much easier to remember and compare shapes to shapes rather than shapes to a button that says the shapes name.
Hopefully my question is clear, and thanks for taking a look!

Yes, you can set the Image property of Button. Alternatively, you can draw non-rectangular buttons, that is, buttons of any shape. The following code demonstrates both techniques:
using System;
using System.Drawing;
using System.Windows.Forms;
class ShapeButton : Button {
public Action<PaintEventArgs> DoPaint { get; set; }
protected override void OnPaint(PaintEventArgs e) {
if (DoPaint != null) { DoPaint(e); }
}
}
static class Program {
static void Main() {
// Ellipse button
ShapeButton ellipseButton = new ShapeButton();
ellipseButton.Location = new Point(10, 10);
ellipseButton.Size = new Size(80, 80);
ellipseButton.DoPaint = delegate(PaintEventArgs e) {
Graphics graphics = e.Graphics;
SolidBrush brush1 = new SolidBrush(SystemColors.ButtonFace);
graphics.FillRectangle(brush1, 0, 0, ellipseButton.Width, ellipseButton.Height);
SolidBrush brush2 = new SolidBrush(Color.Red);
graphics.FillEllipse(brush2, 0, 0, ellipseButton.Width, ellipseButton.Height);
};
ellipseButton.Click += delegate(object sender, EventArgs e) {
MessageBox.Show("Ellipse!");
};
// Triangle button
ShapeButton triangleButton = new ShapeButton();
triangleButton.Location = new Point(100, 10);
triangleButton.Size = new Size(80, 80);
triangleButton.DoPaint = delegate(PaintEventArgs e) {
Graphics graphics = e.Graphics;
SolidBrush brush1 = new SolidBrush(SystemColors.ButtonFace);
graphics.FillRectangle(brush1, 0, 0, triangleButton.Width, triangleButton.Height);
SolidBrush brush2 = new SolidBrush(Color.Green);
Point[] points = {
new Point(triangleButton.Width / 2, 0),
new Point(0, triangleButton.Height),
new Point(triangleButton.Width, triangleButton.Height)
};
graphics.FillPolygon(brush2, points);
};
triangleButton.Click += delegate(object sender, EventArgs e) {
MessageBox.Show("Triangle!");
};
// Star button (using image)
Button starButton = new Button();
starButton.Location = new Point(190, 10);
starButton.Size = new Size(80, 80);
starButton.Image = new Bitmap("Star.png");
starButton.Click += delegate(object sender, EventArgs e) {
MessageBox.Show("Star!");
};
// The form
Form form = new Form();
form.Text = "Shape Button Test";
form.ClientSize = new Size(280, 100);
form.Controls.Add(ellipseButton);
form.Controls.Add(triangleButton);
form.Controls.Add(starButton);
form.ShowDialog();
}
}
Result (after clicking on the triangle button):

In winforms to change the button's image at runtime you can use something like this:
button1.Image = new Bitmap(Image.FromFile(#"Pictures\Koala.jpg"));
It should be added to event handler. For example if you want to show the image when the button is clicked you subscribe to Click event of the button and add the code into the handler method:
private void button1_Click(object sender, EventArgs e)
{
button1.Image = new Bitmap(Image.FromFile(#"Pictures\Koala.jpg"));
}

In my example,
I have a pictureBox to show, two buttons, one to control, one to be drawn.
//odd display, even draw
int count = 0;
Image storePicture;
//whenever the background image changed,store it
private void pictureBoxShow_BackgroundImageChanged(object sender, EventArgs e)
{
//you can stored to a Image array if you have series pictures to show
storePicture = pictureBoxShow.BackgroundImage;
}
private void buttonControl_Click(object sender, EventArgs e)
{
count++;
//odd show picture, even draw picture on button
if (count % 2 == 1)
pictureBoxShow.BackgroundImage = new Bitmap("shapes.JPG");
else
{
//in case you want to clear text on the button
buttonDrawn.Text = null;
//recreate the picture so that it fit the button size
buttonDrawn.Image = new Bitmap(storePicture, new Size(buttonDrawn.Width, buttonDrawn.Height));
}
}
Please remember to attach the handlers to corresponding events. ^^

Why not using PictureBox instead of Buttons.
you have just to add your task to its event/OnClick
Of course you can load any Image to any PictureBox in runtime

The code above is great, however you can click outside the circle within a square containing the circle and get the click event.
If you want to capture the click only if the user clicks inside the shape you have to set the region property with something like this
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
GraphicsPath gp = new GraphicsPath();
gp.AddEllipse(0, 0, 100, 100);
Button1.Region = new Region(gp);
}
}

How do i reset/clear all the drawings i did on pictureBox1?

I have a pictureBox1 with image inside and when i click on it its drawing points.
Now i added a reset button i called it when i click on it its should clear all the drawings i did on the pictureBox and leavethe image inside without the drawings on it.
I did:
private void button4_Click(object sender, EventArgs e)
{
Graphics graphics;
graphics = pictureBox1.CreateGraphics();
graphics.DrawImage(pictureBox1.Image, 0, 0);
}
So i draw a lot of points on pictureBox1 then click the button and all points are gone but then once i click on the picturebox1 again i see also the new points but also the old points i did before the clearing.
How can i clear the old drawings so it wont show up on the next clicks ?
This is the paint event: Moved the paint event to a new class:
public static void Paint(List<PointF> pb1points, GraphicsPath pb1gp, Point movingPoint, PictureBox pictureBox1, Graphics e)
{
e.Clear(Color.White);
e.DrawImage(pictureBox1.Image, movingPoint);
Pen p;
p = new Pen(Brushes.Green);
foreach (PointF pt in pb1points)
{
e.FillEllipse(Brushes.Red, pt.X, pt.Y, 3f, 3f);
}
using (Pen pp = new Pen(Color.Green, 2f))
{
pp.StartCap = pp.EndCap = LineCap.Round;
pp.LineJoin = LineJoin.Round;
e.DrawPath(pp, pb1gp);
}
}

You can try using Graphics.Clear().
Reference: http://msdn.microsoft.com/en-us/library/system.drawing.graphics.clear(v=vs.110).aspx

setting the Image property to null should work.
picBox.Image = null;
Ii it's not worked ,you might be used the InitialImage property to display your image.
pictBox.InitialImage = null;
Please refer the link:
Clear image on picturebox

This is working:
private void button4_Click(object sender, EventArgs e)
{
Graphics graphics;
graphics = pictureBox1.CreateGraphics();
graphics.DrawImage(pictureBox1.Image, 0, 0);
pb1points = new List<PointF>();
}

Apply new colour (with Gradient) to Win Forms button onClick

I've come across several methods of applying gradient styles to objects in a windows form application. All the methods involve overriding the OnPaint method. However, I am looking the change the style at runtime based on validation.
How can I apply the new gradient style to an already rendered button (like I can with BackColor)?
R,
C.
UPDATE: This is the code I am currently using. It appears to have no effect
private void Button_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
Graphics g = e.Graphics;
g.DrawString("This is a diagonal line drawn on the control",
new Font("Arial", 10), System.Drawing.Brushes.Blue, new Point(30, 30));
g.DrawLine(System.Drawing.Pens.Red, btn.Left, btn.Top,
btn.Right, btn.Bottom);
this.btn.Invalidate();
}
Being called by
btn.Paint += new PaintEventHandler(this.Button_Paint);
FURTHER UPDATE WITH CURRENT CODE
private void Button_Paint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
g.DrawString("This is a diagonal line drawn on the control",
new Font("Arial", 10), System.Drawing.Brushes.Blue, new Point(30, 30));
g.DrawLine(System.Drawing.Pens.Red, btn.Left, btn.Top,
btn.Right, btn.Bottom);
}
private void btn_Click(object sender, EventArgs e)
{
btn.Paint += new PaintEventHandler(this.Button_Paint);();
btn.Invalidate();
}

There are two parts to this. One, as SLaks said, you need to draw the gradient in your Paint event handler. This would look something like this (my example here is a bit messy for the sake of brevity):
private void Button_Paint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
if (MyFormIsValid()) {
g.DrawString("This is a diagonal line drawn on the control",
new Font("Arial", 10), System.Drawing.Brushes.Blue, new Point(30, 30));
g.DrawLine(System.Drawing.Pens.Red, btn.Left, btn.Top,
btn.Right, btn.Bottom);
}
else {
g.FillRectangle(
new LinearGradientBrush(PointF.Empty, new PointF(0, btn.Height), Color.White, Color.Red),
new RectangleF(PointF.Empty, btn.Size));
}
}
Also, you need to do your validation and redraw the button when it is clicked:
btn.Click += Button_Click;
...
private void Button_Click(object sender, EventArgs e)
{
DoValidations();
btn.Invalidate();
}
Of course, you'll have to implement the DoValidations() and MyFormIsValid() methods.
Here's the whole thing as a runnable sample program: http://pastebin.com/cfXvtVwT

As you've seen, you need to handle the Paint event.
You can set a boolean in your class to indicate whether to draw the gradient or not.