How to draw, select, re-size & drop the drawing shapes?

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I am creating the video player in that i am drawing shapes using GDI+. By using this i can draw the shapes over the panel. But i need to select the drawn shapes to move & re-size dynamically [To make it more user friendly]. What i have to do to achieve this!?

Thanks & regards,
J.Surjith Kumar

Posted 10-Jun-13 20:21pm

J.Surjith Kumar

Updated 11-Jun-13 20:14pm

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joshrduncan2012 11-Jun-13 9:05am

What have you tried so far to accomplish this?

J.Surjith Kumar 11-Jun-13 10:22am

I tried by creating the glass panel for each and every drawings dynamically but when i play the video, the shapes which i drawn over the glass panel was flickering.

JackDingler 11-Jun-13 15:04pm

You have to be sure that your code draws after each frame, before the frame is blitted to the DC. i don't know specifically how to do this in DirectX, but there should be a call that allows you to hook into the frame for post processing.

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JackDingler · Answer 1 · 2013-06-11T03:20:00

There are two common methods for doing this.

1. Check you cursor coordinates against each shape to see if it comes near any primitive. The downside of this technique is that the more shapes you have on the screen, the more need you'll have for optimizations to prune the selections down, before doing the math to determine if your cursor and shapes are close enough together to count as a selection.

2. With every draw to the screen DC or memory DC, also draw to a memory DC using a false color determined by an ID for the shape or primitive. For this operation disable anti-aliasing, it is designed to smudge the pixel colors and will corrupt the IDs. With a 32 bit bitmap, you can use a DWORD for the ID, giving you up to 2^32-1 shape primitives that can be viewed on the screen. To find the primitive, simply scan the pixels on the false color bitmap and choose the object that is closest to the cursor position. Be sure and paint the background with 0 before every draw. This technique requires no complex math and performs very fast look ups.

The look up for the second one, can be a simple scan of the pixels near the cursor. No need to scan the entire image.