Passing argument to function

[otl1]

Hello Everone, I am trying to modify the function, to pass the argument (xpos, ypos) to the function to be able to write the multiple images on display without defining the multiple functions.
Here is the original Code from the library Flash_PNG example with pngDraw(PNGDRAW *pDraw) function which works fine:

#include <PNGdec.h>
#include "panda.h" // Image is stored here in an 8 bit array
PNG png; // PNG decoder inatance
#define MAX_IMAGE_WDITH 240 // Adjust for your images

int16_t xpos = 0;
int16_t ypos = 0;

#include "SPI.h"
#include <TFT_eSPI.h>              // Hardware-specific library
TFT_eSPI tft = TFT_eSPI();         // Invoke custom library

void setup()
{
  Serial.begin(115200);
  tft.begin();
  tft.fillScreen(TFT_BLACK);
}

void pngDraw(PNGDRAW *pDraw) {
  uint16_t lineBuffer[MAX_IMAGE_WDITH];
  png.getLineAsRGB565(pDraw, lineBuffer, PNG_RGB565_BIG_ENDIAN, 0xffffffff);
  tft.pushImage(xpos, ypos + pDraw->y, pDraw->iWidth, 1, lineBuffer);
}

void loop()
{
  int16_t rc = png.openFLASH((uint8_t *)panda, sizeof(panda), pngDraw);
  if (rc == PNG_SUCCESS) {
    tft.startWrite();
    uint32_t dt = millis();
    rc = png.decode(NULL, 0);
    tft.endWrite();
  }
}

Here is the code with modified function pngDraw(PNGDRAW *pDraw, const int16_t &xpos, const int16_t &ypos) But it's not working:

#include <PNGdec.h>
#include "panda.h" // Image is stored here in an 8 bit array
PNG png; // PNG decoder inatance
#define MAX_IMAGE_WDITH 240 // Adjust for your images

//int16_t xpos = 0;
//int16_t ypos = 0;

#include "SPI.h"
#include <TFT_eSPI.h>              // Hardware-specific library
TFT_eSPI tft = TFT_eSPI();         // Invoke custom library

void setup()
{
  Serial.begin(115200);
  tft.begin();
  tft.fillScreen(TFT_BLACK);
}

void pngDraw(PNGDRAW *pDraw, const int16_t &xpos, const int16_t &ypos) {
  uint16_t lineBuffer[MAX_IMAGE_WDITH];
  png.getLineAsRGB565(pDraw, lineBuffer, PNG_RGB565_BIG_ENDIAN, 0xffffffff);
  tft.pushImage(xpos, ypos + pDraw->y, pDraw->iWidth, 1, lineBuffer);
}

void loop()
{
  int16_t rc = png.openFLASH((uint8_t *)panda, sizeof(panda), pngDraw(PNGDRAW *pDraw, 15, 35));
  if (rc == PNG_SUCCESS) {
    tft.startWrite();
    uint32_t dt = millis();
    rc = png.decode(NULL, 0);
    tft.endWrite();
  }
}

Am I missing something here?
Thanks in Advance!

[Bodmer]

The functions you are trying to adapt are part of the PNGdec library. You would need to modify the source code in that library.

The simplest option is to use the original example sketch approach and just set xpos and ypos variables to the desired position before calling png.openFLASH.