RC6: Rendering parts of one cairo surface to another

[tmighty2]

Hello!

I am loading an image of a button into a cairo surface.

I have attached it.

I want to render this button as various sizes without stretching it.
Therefore I try to render the top left corner to another surface, then the top right corner, then the top middle section (in a stretched way to allow for different button sizes).

I believe this approach is well know.

I am stuck because RC6 RenderSurface does not behave like BitBlt which has 2 more parameters. Instead it creates a stretched render.

Can somebody suggest a solution?

I have attached another version on which numbers are printed that show where stretching / shrinking occurs.

Thank you.

[jpbro]

Not sure if there's a better way, but one option would be to create a rectangle path for each corner at the size you want, then call TranslateDrawings to "offset" the rendering, and finally Fill the path with a surface pattern. Something like this:

   Cairo.ImageList.AddImage "button", "path to a button image file"   ' Add a button image to the Cairo ImageList with the key "button"
   
   With New_c.Cairo.CreateSurface(1000, 1000)
      With .CreateContext
         .Rectangle 100, 100, 16, 16   ' Create a 16x16 rectangle path at 100px from the top-left corner of the surface
         .TranslateDrawings 100, 100   ' Translate the drawings so the top-left corner of the button surface appears at 100x100
         .Fill , Cairo.ImageList("button").CreateSurfacePattern   ' Fill the path with the button image
      End With
   End With

[tmighty2]

Thank you. It works.
It even works when I draw a rectangle that exceeds the size of the surface. I expected that this would throw an error, but it does not.

I don't understand why these 2 arguments were left out that would make RenderSurfaceContent behave like BitBlt. I miss that, and while you have shown me a solution now, I find it unexcepted that I must do it like this.
ps: I really really like the syntax of cCairoSurface and cCairoContext. It is very beautiful code! That is why I ask myself what the deal with the 2 left-out arguments is.