Develop Reference

zoom an image in a second picturebox following cursor

i have a picturebox that contain an image (1280 X 720), i want to create a second picturebox that contain a zoomed version of the image centered around the cursor (for example a 40 X 40 square around the cursor zomed to be in a 120 X 120 square picturebox) that follow the cursor in real time in real time (if it's possible also to have a cross in the middle of the picturebox that show the precise placing of the cursor is even better).
private void Button1_Click(object sender, EventArgs e)
{
openFileDialog1.Filter = "All jpg files (*.jpg)|*.jpg";
if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
Bitmap img = new Bitmap(openFileDialog1.FileName);
double imageHeight = img.Height;
double imageWidth = img.Width;
pictureBox1.Image = img;
}
}
private void PictureBox1_MouseMove(object sender, MouseEventArgs e)
{
int xupleft = e.X - 20;
int yupleft = e.Y - 20;
Rectangle myrectangle = new Rectangle(xupleft, yupleft, 40, 40);
pictureBox2.Image = pictureBox1.Image;
}

Here is a simple example with the layout I described in the comment:
Both PictureBoxes are nested in Panels.
The first one is in Zoom mode and upon loading a file its size is adapted to avoid blank stripes to the sides. Its parent panel is used to reset to the maximum allowed size.
The 2nd one is in AutoSize mode and its parent panel is used to 1) hide the outer portions and 2) to calculate the offset to center the image.
Here is the simple Paint event for pbox1:
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
Size sz = pictureBox1.ClientSize;
Point pt = pictureBox1.PointToClient(Control.MousePosition);
e.Graphics.DrawLine(Pens.OrangeRed, pt.X, 0, pt.X, sz.Height);
e.Graphics.DrawLine(Pens.OrangeRed, 0, pt.Y, sz.Width, pt.Y);
}
Here is the MouseMove the triggers the Paint and moves pbox2:
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
pictureBox1.Invalidate();
float f = 1f * pictureBox2.ClientSize.Width / pictureBox1.ClientSize.Width;
Size s2 = pictureBox2.Parent.ClientSize;
Point p2 = Point.Round(new PointF(s2.Width/2 - e.X * f , s2.Height/2 - e.Y * f ));
pictureBox2.Location = p2;
}
The file loading is a bit tricky, as it needs to analyze the aspect ratios of image and pbox:
void loadFile(string fileName)
{
if (File.Exists(fileName))
{
pictureBox1.Size = panel1.ClientSize;
pictureBox1.Location = Point.Empty;
pictureBox1.Image = Image.FromFile(fileName);
pictureBox2.Image = Image.FromFile(fileName);
pictureBox2.Location = Point.Empty;
}
Size csz = pictureBox1.ClientSize;
Size isz = pictureBox1.Image.Size;
float iar = 1f * isz.Width / isz.Height; // aspect..
float car = 1f * csz.Width / csz.Height; //..ratios
if (iar < car)
{
pictureBox1.ClientSize = new Size((int)(pictureBox1.ClientSize.Height * iar),
pictureBox1.ClientSize.Height);
}
else if (iar > car)
{
pictureBox1.ClientSize = new Size((pictureBox1.ClientSize.Width,
(int)(pictureBox1.ClientSize.Width / iar));
}
}
Note that before loading the new images one should Dispose of the previous images! Also that after setting the pbox2.SizeMode to Autosize one could set it to Zoom and scale its Size up or down to zoom in or out, if one keeps the aspect ratio the same.
Result:

How to use windows forms report with radial gauge

I tried to find information on how to use a radial gauge in a windows form report.
I really can't find anything on this. Not sure if there is not much info on this.
Is there anyone who can get me some info on this? How would I be able to use a value from a text box in a report viewer to show this on a radial gauge and even using a track bar to get some idea how to use it.
Even if getting a small example to build on this would be really great :-)

You have several options even without any external stuff.
You can draw a gauge needle onto a gauge image. Here is an example.
You can draw the needle onto an image by either calulating the outer point and drawing a line to the center or by rotating the canvas as in the link.
Or you can use the built-in MSChart control and its Doughnut charttype.
Here is an example for this:
The code is simple:
first we set up the chart by adding three DataPoints; then we code a function to update the value.
The points are for
the open, transparent part
the value of the gauge in green
the rest of the scale in red
For testing I use these variables:
double valMin = 0; // user data minimum
double valMax = 100; // ~ maximum
float angle = 60; // open pie angle at the bottom
string valFmt = "{0}°"; // a format string
My current value is pulled from a trackbar.
Setup code:
void setupChartGauge(double val, double vMin, double vMax, float a)
{
valMin = vMin;
valMax = vMax;
angle = a;
Series s = gaugeChart.Series[0];
s.ChartType = SeriesChartType.Doughnut;
s.SetCustomProperty("PieStartAngle", (90 - angle/2) + "");
s.SetCustomProperty("DoughnutRadius", "10");
s.Points.Clear();
s.Points.AddY(angle);
s.Points.AddY(0);
s.Points.AddY(0);
setChartGauge(0);
s.Points[0].Color = Color.Transparent;
s.Points[1].Color = Color.Chartreuse;
s.Points[2].Color = Color.Tomato;
}
and setting a value:
void setChartGauge(double val)
{
Series s = gaugeChart.Series[0];
double range = valMax - valMin;
double aRange = 360 - angle;
double f = aRange / range;
double v1 = val * f;
double v2 = (range - val) * f;
s.Points[1].YValues[0] = v1;
s.Points[2].YValues[0] = v2;
gaugeChart.Titles[0].Text = String.Format(valFmt, val);
gaugeChart.Refresh();
}
I have added minimal styling:
The Chart has a Title docked centered bottom which I also update
I have set a back color
I paint an inner circle in the Paint event like so:
e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
Rectangle r = chart1.ClientRectangle;
r.Inflate(-10, -10);
using (SolidBrush brush = new SolidBrush(Color.FromArgb(55, Color.Beige)))
e.Graphics.FillEllipse(brush, r);
Note that Pie and Doughnut charts can have only one series. To show a 2nd one you would need an overlapping 2nd chartarea with the exact same Position.
There are infinite ways to draw stuff, both from scratch or updating the MsChart control. Various gradient brushes come to mind. Adding ticks and a needle will involve rotation code, which basically consists of 3 lines of code..
Update:
Here is an example of drawing a gauge needle.
The code should be called from a Paint event and should pass out a valid Graphics object (read: e.Graphics), a float for the data value, a Rectangle to place the gauge in, a Color and a float for the percentage of the rectangle size to use.
private void drawNeedle(Graphics g, float val, Rectangle r, Color c, float length)
{
Point pc = new Point(r.X + r.Width / 2, r.Y + r.Height / 2);
Point p2 = new Point((int)( pc.X + r.Width / 2 * length / 100f), pc.Y);
using (Pen pen = new Pen(c, 3f)
{ StartCap = LineCap.RoundAnchor, EndCap = LineCap.ArrowAnchor })
{
g.SmoothingMode = SmoothingMode.AntiAlias;
g.TranslateTransform(pc.X, pc.Y);
g.RotateTransform(val - (270 - angle / 2));
g.TranslateTransform(-pc.X, -pc.Y);
g.DrawLine(pen, pc, p2);
g.ResetTransform();
}
}
You can use it in any control that support owner-drawing including the chart..:
drawNeedle(e.Graphics, (float)gaugeChart.Series[0].Points[1].YValues[0], r, Color.White, 70f);

Here is a simple example with a TrackBar:
private Syncfusion.Windows.Forms.Gauge.RadialGauge radialGauge1;
private System.Windows.Forms.TrackBar trackBar1;
private Syncfusion.Windows.Forms.Gauge.Needle needle1;
private void InitializeComponent()
{
this.needle1 = new Syncfusion.Windows.Forms.Gauge.Needle();
this.needle1.Value = 0F;
this.trackBar1 = new System.Windows.Forms.TrackBar();
this.radialGauge1 = new Syncfusion.Windows.Forms.Gauge.RadialGauge();
this.trackBar1.Value = (int) needle1.Value;
this.radialGauge1.EnableCustomNeedles = true;
this.radialGauge1.NeedleCollection.Add(needle1);
this.radialGauge1.Size = new System.Drawing.Size(230, 230);
this.radialGauge1.TabIndex = 0;
this.trackBar1.Scroll += new System.EventHandler(this.trackBar1_Scroll);
}
And a scroll event which sync between gauge and trackBar:
private void trackBar1_Scroll(object sender, EventArgs e)
{
needle1.Value = trackBar1.Value;
}

How to Draw a Rubber Band Selection Rectangle accurately on a Rotated Canvas?

This is a rubber band selection rectangle drawn on a canvas. My problem is that it is easy to get the correct size of the rectangle provided the canvas contents are not rotated. But as soon as it is rotated the rectangle no longer sizes with the cursor. I need the rubber band to stay parallel with screen
var dragPt = new PointF(e.Position.X - G.ReferenceOffset.X, e.Position.Y - G.ReferenceOffset.Y);
var rotation = ADEEnvironment.RotateAngle;
var width = (dragPt.X - pressPt.X);
var height = (dragPt.Y - pressPt.Y);
The code is pretty trivial. I capture the position of the mouse on mouse down: pressPt. In the mouse move event I get the current mouse position dragPt and calculate the width and height of the rubber band rectangle and use those values to create a rectangle with its origin on pressPt.
This works fine if the camera for the canvas is not rotated. When I rotate the display I need the rubber band to stay aligned with the screen and not the canvas it is drawn on. It I just leave it the rubber band is drawn rotated as well.
If I rotate the rubber band rectangle to return it to alignment with the screen then the rectangle is no longer sizing correctly. So after a lot of messing about I tried a bit of trigonometry:
var width = (float)((dragPt.X - pressPt.X) / Math.Cos(rotation));
var height = (float)((dragPt.Y - pressPt.Y) / Math.Cos(rotation));
Which doesn't work and gets very messy given that the rotation angle can be anything for 0 > 360
I have looked at other code on how to create a selection rectangle including the answers to this question: How to make a resizeable rectangle selection tool?
but I would like to use the basic code I have if possible since it is related to the graphics engine I am using (Piccolo).
I would put up some screenshots but I can't capture the rubber band. I think this is more of a math problem than anything else and it ought to be easy to fix but I just can't work out what math calculations to make to account to the effect of rotating the display.

This code uses the Paint event to draw
One fixed rectangle on a rotated canvas
An unrotated copy of it
An unrotated rubber-band
and checks on the corners of example rectanlge
// one example 'object'
Rectangle R0 = new Rectangle(182,82,31,31);
// a few helpers
Point curMouse = Point.Empty;
Point downMouse = Point.Empty;
Rectangle RM = Rectangle.Empty;
float angle = 30;
Point center = new Point(-55, -22);
private void canvas_Paint(object sender, PaintEventArgs e)
{
// preprare the canvas to rotate around a center point:
e.Graphics.TranslateTransform(center.X , center.Y);
e.Graphics.RotateTransform(angle);
e.Graphics.TranslateTransform(-center.X, -center.Y);
// draw one object and reset
e.Graphics.DrawRectangle(Pens.Green, R0);
e.Graphics.ResetTransform();
// for testing (and hittesting): this is the unrotated obejct:
e.Graphics.DrawRectangle(Pens.LightGray, R0);
// allowing for any way the rubber band is drawn..
// ..should be moved to a helper function!
Size S = new Size( Math.Abs(downMouse.X - curMouse.X),
Math.Abs(downMouse.Y - curMouse.Y));
Point P0 = new Point(Math.Min(downMouse.X, curMouse.X),
Math.Min(downMouse.Y, curMouse.Y));
RM = new Rectangle(P0, S);
// the ruber band
e.Graphics.DrawRectangle(Pens.Red, RM);
}
private void canvas_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
curMouse = e.Location;
canvas.Invalidate();
}
private void canvas_MouseDown(object sender, MouseEventArgs e)
{
downMouse = e.Location;
curMouse = e.Location;
}
IMO, the more interesting part will be to decide which objects are selected. Will any intersection count or should it be completely contained?
I found a nice piece of rotation code in this post and add it with an example to check on the fixed Rectangle.
Of course more complex object will call for more involved lists of points. To get really exact results you may even need to go for GraphicsPaths and the set operations on Regions they support; but maybe a simple convex hull will do..
Of course, you will want to store the rotated points instead of reapeatedly calculating them..
static Point RotatePoint(Point pointToRotate, Point centerPoint, double angleInDegrees)
{
double angleInRadians = angleInDegrees * (Math.PI / 180);
double cosTheta = Math.Cos(angleInRadians);
double sinTheta = Math.Sin(angleInRadians);
return new Point
{
X =
(int)
(cosTheta * (pointToRotate.X - centerPoint.X) -
sinTheta * (pointToRotate.Y - centerPoint.Y) + centerPoint.X),
Y =
(int)
(sinTheta * (pointToRotate.X - centerPoint.X) +
cosTheta * (pointToRotate.Y - centerPoint.Y) + centerPoint.Y)
};
}
private void canvas_MouseUp(object sender, MouseEventArgs e)
{
List<Point> points = new List<Point>();
points.Add(RotatePoint(new Point(R0.Left, R0.Top), center, angle));
points.Add(RotatePoint(new Point(R0.Right, R0.Top), center, angle) );
points.Add(RotatePoint(new Point(R0.Right, R0.Bottom), center, angle) );
points.Add(RotatePoint(new Point(R0.Left, R0.Bottom), center, angle));
bool ok = true;
foreach (Point pt in points) if (!RM.Contains(pt)) ok = false;
if (ok) this.Text = "HIT"; else this.Text = "no hit";
}

How to instantiate images upon user click in windows forms

I have small Image for a circle and I want to make the following:
Whenever some place on my form is clicked, I want to add a new instance of that circle in that place if there is no other circle there already.
I was thinking about a list of Circles and when that click happens i check the list to see if none of its circles is overlapping before adding the new one but I don't have any experience with forms so i don't know what would be the best approach for that.

You can build up a GraphicsPath and check if the clicked point is inside any of its parts with the IsVisible method.
This code also builds up a list of the points and to draws the image to each of it in the Paint event. If you let the GraphicsPath do the drawing you uncomment the DrawPath line and delete these //** list related lines.
GraphicsPath GP = new GraphicsPath();
List<Point> PL = new List<Point>(); //**
private void Form1_MouseClick(object sender, MouseEventArgs e)
{
int diameter = 22; // put in the size of your circle
Size s = new Size(diameter, diameter);
if (!GP.IsVisible(e.Location))
{
Point middle = new Point(e.X - diameter / 2, e.Y - diameter / 2);
GP.AddEllipse(new Rectangle(middle, s));
PL.Add(middle); //**
}
this.Invalidate();
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
// e.Graphics.DrawPath(Pens.Firebrick, GP);
Image img = new Bitmap("D:\\circle22.png"); //**
foreach(Point pt in PL) e.Graphics.DrawImage(img, pt); //**
img.Dispose(); //**
}

C# : GDI+ Image cropping

I have an image .I want to crop 10 px from left and 10px from right of the image.I used the below code to do so
string oldImagePath="D:\\RD\\dotnet\\Images\\photo1.jpg";
Bitmap myOriginalImage = (Bitmap)Bitmap.FromFile(oldImagePath);
int newWidth = myOriginalImage.Width;
int newHeight = myOriginalImage.Height;
Rectangle cropArea = new Rectangle(10,0, newWidth-10, newHeight);
Bitmap target = new Bitmap(cropArea.Width, cropArea.Height);
using (Graphics g = Graphics.FromImage(target))
{
g.DrawImage(myOriginalImage,cropArea);
}
target.Save("D:\\RD\\dotnet\\Images\\test.jpg");
But this is not giving me the results which i expect. This outputs an image which has 10 px cropped from the right and a resized image.Instead of cropiing it is resizing the width i think.So the image is shrinked(by width). Can any one correct me ? Thanks in advance

Your new width should be reduced by twice the crop margin, since you'll be chopping off that amount from both sides.
Next, when drawing the image into the new one, draw it at a negative offset. This causes the area that you aren't interested in to be clipped off.
int cropX = 10;
Bitmap target = new Bitmap(myOriginalImage.Width - 2*cropX, myOriginalImage.Height);
using (Graphics g = Graphics.FromImage(target))
{
g.DrawImage(myOriginalImage, -cropX, 0);
}

My guess is this line
Rectangle cropArea = new Rectangle(10,0, newWidth-10, newHeight);
should be
Rectangle cropArea = new Rectangle(10,0, newWidth-20, newHeight);
Set the width of the new rectangle to be 20 less than the original - 10 for each side.
Some indication what result it is giving you would be helpful in confirming this.

Corey Ross is correct. Alternately, you can translate along the negative x axis and render at 0.0, 0.0. Should produce identical results.
using (Graphics g = Graphics.FromImage(target))
{
g.TranslateTransform(-cropX, 0.0f);
g.DrawImage(myOriginalImage, 0.0f, 0.0f);
}

You need to use the overload that has you specify both Destination Rectangle, and Source Rectangle.
Below is an interactive form of this using a picture box on a form. It allows you to drag the image around. I suggest making the picture box 100 x 100 and have a much larger image such as a full screen window you've captured with alt-prtscr.
class Form1 : Form
{
// ...
Image i = new Bitmap(#"C:\Users\jasond\Pictures\foo.bmp");
Point lastLocation = Point.Empty;
Size delta = Size.Empty;
Point drawLocation = Point.Empty;
bool dragging = false;
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
if (!dragging)
{
lastLocation = e.Location;
dragging = true;
}
delta = new Size(lastLocation.X - e.Location.X, lastLocation.Y - e.Location.Y);
lastLocation = e.Location;
if (!delta.IsEmpty)
{
drawLocation.X += delta.Width;
drawLocation.Y += delta.Height;
pictureBox1.Invalidate();
}
}
else
{
dragging = false;
}
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
Rectangle source = new Rectangle(drawLocation,pictureBox1.ClientRectangle.Size);
e.Graphics.DrawImage(i,pictureBox1.ClientRectangle,source, GraphicsUnit.Pixel);
}
//...

Okay, I totally fail at explaining this, but hang on:
The DrawImage function requires the location of the image, as well as it's position. You need a second position for cropping as how the old relates to the new, not vice versa.
That was entirely incomprehensible, but here is the code.
g.DrawImage(myOriginalImage, -cropArea.X, -cropArea.Y);
I hope that explains it more then I did.