| Googled and found a macro... #define RGB(R,G,B) {(R<<16)|(G<<8)|B,(R*65535)/255,(G*65535)/255,(B*65535)/255} I have tried it with a handful of rgb values and it works (used gtk_widget_modify_bg to change the surface colour of some dialogs), like GdkColor col = RGB(0,0,255); gtk_widget_modify_bg ( dlg , GTK_STATE_NORMAL , &col ); A few changes were needed to my api. For example, on Windows I returned colorrefs as int function values. That is not possible for GdkColor structs, so I changed the api to return a COLORREF parameter instead with typedef GdkColor COLORREF; // for Gtk typedef int COLORREF; // for Windows It works, but I still don't understand colours... Q1. the pixel component of the GdkColor struct is (R<<16)|(G<<8)|B, but is the other way around in the Windows RGB macro R|(G<<16)|(B<<16). I am puzzled by this. I am also puzzled by the pixel value being 32 bits (r,g,b,alpha) while the combined size of the r,g,b intensities is 48. Why is this? Q2. while googling I came across this for GdkColor: 'the programmer provides the r,g and b intensities and GDK fills in the pixel component.' When does GDK do this? By what functions? Q3. I have tried reading about Colormaps and Colors in the GDK reference manual, but I am getting stuck on the basics. For example in the Description what does this mean: 'A colormap is an object that contains the mapping between the color values stored in memory and the RGB values that are used to display color values. In general, colormaps only contain significant information for pseudo-color visuals, but even for other visual types, a colormap object is required in some circumstances.' Does it mean 'a colormap is a list of GdkColors like a palette'? Is the RGB value mentioned in the description the pixel component in the GdkColor? Q4. For GdkColor the manual says 'the GdkColor structure is used to describe an allocated or unallocated color'. What does allocated and unallocated color mean? Q5. The Colormaps and Colors Reference contains several functions, but I did not use any of them. It still worked with the colours coming out the way I expected. When are these functions used/needed? Or are they becoming obsolete? --- On Fri, 13/8/10, Ken Resander <kresander@xxxxxxxxx> wrote:
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