I'm trying to make a program to draw on the a Panel
(a square, circle, etc...) by clicking on a button.
I have not done much so far, just tried the code drawing directly to the panel but don't know how to move it to the button. Here is the code I have so far.
If you know a better method to draw than the one I'm using please let me know.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void mainPanel_Paint(object sender, PaintEventArgs e)
{
Graphics g;
g = CreateGraphics();
Pen pen = new Pen(Color.Black);
Rectangle r = new Rectangle(10, 10, 100, 100);
g.DrawRectangle(pen, r);
}
private void circleButton_Click(object sender, EventArgs e)
{
}
private void drawButton_Click(object sender, EventArgs e)
{
}
}
}
Using this extremely simplified example class..:
class DrawAction
{
public char type { get; set; }
public Rectangle rect { get; set; }
public Color color { get; set; }
//.....
public DrawAction(char type_, Rectangle rect_, Color color_)
{ type = type_; rect = rect_; color = color_; }
}
Have a class level List<T>
:
List<DrawAction> actions = new List<DrawAction>();
you would code a few buttons like this:
private void RectangleButton_Click(object sender, EventArgs e)
{
actions.Add(new DrawAction('R', new Rectangle(11, 22, 66, 88), Color.DarkGoldenrod));
mainPanel.Invalidate(); // this triggers the Paint event!
}
private void circleButton_Click(object sender, EventArgs e)
{
actions.Add(new DrawAction('E', new Rectangle(33, 44, 66, 88), Color.DarkGoldenrod));
mainPanel.Invalidate(); // this triggers the Paint event!
}
And in the Paint
event:
private void mainPanel_Paint(object sender, PaintEventArgs e)
{
foreach (DrawAction da in actions)
{
if (da.type == 'R') e.Graphics.DrawRectangle(new Pen(da.color), da.rect);
else if (da.type == 'E') e.Graphics.DrawEllipse(new Pen(da.color), da.rect);
//..
}
}
Also use a double-buffered Panel
subclass:
class DrawPanel : Panel
{
public DrawPanel()
{ this.DoubleBuffered = true; BackColor = Color.Transparent; }
}
The next steps will be to add more types, like lines, curve, text; also colors, pen widths and styles. Also make it dynamic, so that you pick a tool and then click at the Panel..
For freehand drawing you need to collect a List<Point>
in the MouseMove
etc..
Lots of work, lots of fun.
Updates from comments:
Note: This is, as I wrote extremely simplified. I have character to draw shapes like Rectangle and Ellipse. With a little more code you can add more characters for a filled rectangle and a filledEllipse. But a) the shapes really ought to be in an Enum and b) more complicated shapes like lines, polygons, text, or shapes with rotation will need more data that just a Rectangle. .
The restriction to rectangle coodinates was a simplification, not so much of the shape but of the data structure. Your other shapes could be reduced to fit in a rectangle (four triangles and two hexagons come to mind); just add charcters and new drawxxx calls.. But evetually adding a List for complex shapes and maybe a string and a font will allow for more complex results..
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