Examples: DirectX10/11/12, Allegro, Marmalade: Render functions early out when display size is zero (minimized). (#2496)

examples/imgui_impl_dx12.cpp

@@ -62,6 +62,10 @@ struct VERTEX_CONSTANT_BUFFER
 // (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from your main loop)
 void ImGui_ImplDX12_RenderDrawData(ImDrawData* draw_data, ID3D12GraphicsCommandList* ctx)
 {
+    // Avoid rendering when minimized
+    if (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f)
+        return;
+
     // FIXME: I'm assuming that this only gets called once per frame!
     // If not, we can't just re-allocate the IB or VB, we'll have to do a proper allocator.
     g_frameIndex = g_frameIndex + 1;