GUI_PNG_Draw no image shown on STM32F4 platform

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    • GUI_PNG_Draw no image shown on STM32F4 platform

      Hello
      i try to use GUI_PNG_Draw, to print an image on STM32F429 EVAL platform, but the image doesn't appears.


      What could be the problem ? (it runs well in simulator and it runs well for *.bmp file but fails for *.jpeg also)

      thanks for any support

    • Hi,

      Do you have enough memory available for drawing PNG/JPEG file?

      The RAM requirement for PNG is:

      (xSize + 1) * ySize * 4 + 54 Kbytes

      For JPEG the RAM requirement is:

      xSize * 80 bytes + 33 Kbytes

      The memory gets allocated from the GUI_MEMORY which gets set by GUI_ALLOC_AssignMemory().

      egards,
      Sven
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    • Hello,
      thank you for your reply.
      In the project there is a call to GUI_ALLOC_AssignMemory(aMemory, GUI_NUMBYTES); with GUI_NUMBYTES = (1024) * 140;
      This memory is allocated for general use of emWin ?


      That is to say that if i want to use a 13*13 PNG file i have to allocate 14*13*4 + 54Kbytes = 56Kbytes ; so i must define GUI_NUMBYTES = (1024) * (140+56) ?

      Thanks in advance

      best regards

    • I found a bug in the emWinPng library when using ARGB color space with no Alpha setting the Alpha channel was being set to transparent.

      In the V540 version of the file:
      GUI_PNG.c line 400 change the line for assigning the Color to:
      #if (GUI_USE_ARGB)
      Color = b + ((U16)g << 8 ) + ((U32)r << 16) + ((U32)(255) << 24);
      #else