Clicable line!!

Question

Hi guys, I wonder if anyone knows how to draw a line that u can click later to edit properties like color. Pretty much like word drawing tool. Any thougts are welcome!! Thanks in advance!!

ee95110 · Answer

Hum thanks spgilmore, i resolved the problem by defining 2 lines one on each side of the line to evaluate within 3 px. I then evaluate the line equation to find if a givem point was on the line. I do this every time mousemove event fires. Thanks for the help. By the way i can only have lines int my application.

spgilmore · Answer

I've had this discussion before. You may also run into the possibility of multiple objects in the same rectangular region. You will have to make a determination which is which. Consider, too, that you may have MANY objects rects to search through. The solution seems to be this; Take the point that was clicked and find all "objects" (lines, boxes, etc.) that may qualify as the selected object, that is, all the objects whose rectangles span the clicked point. This cuts calculation time by narrowing the objects that need to be evaluated. Each object type should have a means of determining if the clicked point actually selected it. Boxes should look for the point in their borders. Circles, lines, beziers and other primitives may have to actually be CALCULATED as a set of points to determine if the clicked point was on the line, border, etc. After that step, you may still have multiple objects to choose from. How you do this is up to you. You may choose to use a Z-order, a random object, or the last one added. This depends on your application.

ssswamii · Answer

Perhaps you could use a System.Drawing.Region instead of a rectangle for odd shapes?

ee95110 · Answer

The problem is oblique lines. No way to define the rectangular region...

ee95110 · Answer

Thanks Judah, it worked, i stored all the instances of my class in a queue. Ty.

ssswamii · Answer

Yes. Create a class called Line that contains a System.Drawing.Rectangle specifying the coordinates and boundaries of the line drawn. When the user clicks your control, go through all your line classes and see if the click point was within the System.Drawing.Rectangle stored in each Line class instance.

Clicable line!!

Answers (6)