Difference between revisions of "Drawing with canvas"
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'''Drawing with canvas''' can be done using several procedures e.g. | '''Drawing with canvas''' can be done using several procedures e.g. | ||
| − | * [[Canvas line]], draws a line from coordinates (x1, y1) to (x2, y2) | + | * [[Canvas line]], draws a line from coordinates (x1,y1) to (x2,y2) |
| − | * [[Canvas rectangle]], draws a rectangle from upper left (x1, y1) to lower right (x2, y2) | + | * [[Canvas rectangle]], draws a rectangle from upper left (x1,y1) to lower right (x2,y2) |
| − | * [[Canvas ellipse]], draws an ellipse in | + | * [[Canvas ellipse]], draws an ellipse in a rectangle defined by (x1,y1) and (x2,y2). If x2-x1 = y2-y1, the ellipse will be a circle with radius (x2-x1)/2. |
| − | The following code draws the diagonals. Enter the code between | + | |
| + | The following code draws the diagonals of the canvas. Enter the code between ''begin'' and ''end'' of the procedure Button1Click: | ||
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| − | In the Canvas object | + | In the Canvas object the ''Brush'' and ''Pen'' objects are defined, both with a ''color'' property, which indicate the color that makes the fill and stroke of the various objects that are drawn. To paint an object of one color, the first thing is to change the brush and color, before giving the instruction to draw, the order of the statements is important. This would be the code, notice how the color is changed before drawing the ellipse: |
| − | To paint an object of one color, the first thing is to change the brush and color, before giving the instruction to draw, the order of the statements is important. This would be the code, notice how the color is changed | ||
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Revision as of 12:02, 6 November 2016
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Drawing with canvas can be done using several procedures e.g.
- Canvas line, draws a line from coordinates (x1,y1) to (x2,y2)
- Canvas rectangle, draws a rectangle from upper left (x1,y1) to lower right (x2,y2)
- Canvas ellipse, draws an ellipse in a rectangle defined by (x1,y1) and (x2,y2). If x2-x1 = y2-y1, the ellipse will be a circle with radius (x2-x1)/2.
The following code draws the diagonals of the canvas. Enter the code between begin and end of the procedure Button1Click:
procedure TForm1.Button1Click(Sender: TObject);
begin
canvas.Line(0,0, form1.Width,form1.Height);
canvas.Line(0,form1.height,form1.width,0);
end;In the Canvas object the Brush and Pen objects are defined, both with a color property, which indicate the color that makes the fill and stroke of the various objects that are drawn. To paint an object of one color, the first thing is to change the brush and color, before giving the instruction to draw, the order of the statements is important. This would be the code, notice how the color is changed before drawing the ellipse:
canvas.Brush.color:= clred;
canvas.Ellipse(195, 117, 205, 128);
canvas.Brush.color:= clblue;
canvas.Rectangle (192, 130,208,160);
canvas.Brush.color:= clgreen;
canvas.Rectangle (187, 130,191,162);
canvas.Brush.color:= clyellow;
canvas.Rectangle (209, 130,213,162);
canvas.Brush.color:= clmaroon;
canvas.Rectangle (193,161,199,200);
canvas.Brush.color:= clpurple;
canvas.Rectangle (201,161,207,200);or shorter
with canvas do begin
Brush.color:= clred;
Ellipse(195, 117, 205, 128);
Brush.color:= clblue;
Rectangle (192, 130,208,160);
Brush.color:= clgreen;
Rectangle (187, 130,191,162);
Brush.color:= clyellow;
Rectangle (209, 130,213,162);
Brush.color:= clmaroon;
Rectangle (193,161,199,200);
Brush.color:= clpurple;
Rectangle (201,161,207,200);
end;This will give something like this:
