ImFontAtlas: Added IsBuilt() helper.

imgui.h

@@ -1627,7 +1627,7 @@ enum ImFontAtlasFlags_
 //  2. Call GetTexDataAsAlpha8() or GetTexDataAsRGBA32() to build and retrieve pixels data.
 //  3. Upload the pixels data into a texture within your graphics system.
 //  4. Call SetTexID(my_tex_id); and pass the pointer/identifier to your texture. This value will be passed back to you during rendering to identify the texture.
-// IMPORTANT: If you pass a 'glyph_ranges' array to AddFont*** functions, you need to make sure that your array persist up until the ImFont is build (when calling GetTextData*** or Build()). We only copy the pointer, not the data.
+// IMPORTANT: If you pass a 'glyph_ranges' array to AddFont*** functions, you need to make sure that your array persist up until the ImFont is build (when calling GetTexData*** or Build()). We only copy the pointer, not the data.
 struct ImFontAtlas
 {
     IMGUI_API ImFontAtlas();
@@ -1648,6 +1648,7 @@ struct ImFontAtlas
     // RGBA32 format is provided for convenience and compatibility, but note that unless you use CustomRect to draw color data, the RGB pixels emitted from Fonts will all be white (~75% of waste). 
     // Pitch = Width * BytesPerPixels
     IMGUI_API bool              Build();                    // Build pixels data. This is called automatically for you by the GetTexData*** functions.
+    IMGUI_API bool              IsBuilt()                   { return Fonts.Size > 0 && (TexPixelsAlpha8 != NULL || TexPixelsRGBA32 != NULL); }
     IMGUI_API void              GetTexDataAsAlpha8(unsigned char** out_pixels, int* out_width, int* out_height, int* out_bytes_per_pixel = NULL);  // 1 byte per-pixel
     IMGUI_API void              GetTexDataAsRGBA32(unsigned char** out_pixels, int* out_width, int* out_height, int* out_bytes_per_pixel = NULL);  // 4 bytes-per-pixel
     void                        SetTexID(ImTextureID id)    { TexID = id; }