Add PNG image render examples

examples/PNG Images/Flash_PNG/Flash_PNG.ino

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+
+// This example renders a png file that is stored in a FLASH array
+// using the PNGdec library (available via library manager).
+
+#include <LittleFS.h>
+#define FileSys LittleFS
+
+// Include the PNG decoder library
+#include <PNGdec.h>
+#include "panda_png.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 the TFT library https://github.com/Bodmer/TFT_eSPI
+#include "SPI.h"
+#include <TFT_eSPI.h>              // Hardware-specific library
+TFT_eSPI tft = TFT_eSPI();         // Invoke custom library
+
+//====================================================================================
+//                                    Setup
+//====================================================================================
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println("\n\n Using the PNGdec library");
+
+  // Initialise the TFT
+  tft.begin();
+  tft.fillScreen(TFT_BLACK);
+
+  Serial.println("\r\nInitialisation done.");
+}
+
+//====================================================================================
+//                                    Loop
+//====================================================================================
+void loop()
+{
+  int16_t rc = png.openFLASH((uint8_t *)panda_png, sizeof(panda_png), pngDraw);
+  if (rc == PNG_SUCCESS) {
+    Serial.println("Successfully png file");
+    Serial.printf("image specs: (%d x %d), %d bpp, pixel type: %d\n", png.getWidth(), png.getHeight(), png.getBpp(), png.getPixelType());
+    tft.startWrite();
+    uint32_t dt = millis();
+    rc = png.decode(NULL, 0);
+    Serial.print(millis() - dt); Serial.println("ms");
+    tft.endWrite();
+    // png.close(); // not needed for memory->memory decode
+  }
+  delay(3000);
+  tft.fillScreen(random(0x10000));
+}
+
+
+//=========================================v==========================================
+//                                      pngDraw
+//====================================================================================
+// This next function will be called during decoding of the png file to
+// render each image line to the TFT.  If you use a different TFT library
+// you will need to adapt this function to suit.
+// Callback function to draw pixels to the display
+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);
+}

examples/PNG Images/LittleFS_PNG/LittleFS_PNG.ino

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+
+// This example if for processors with LittleFS capability (e.g. RP2040,
+// ESP32, ESP8266). It renders a png file that is stored in LittleFS
+// using the PNGdec library (available via library manager).
+
+// The test image is in the sketch "data" folder (press Ctrl+K to see it).
+// You must upload the image to LittleFS using the Arduino IDE Tools Data
+// Upload menu option (you may need to install extra tools for that).
+
+// Don't forget to use the Arduino IDE Tools menu to allocate a LittleFS
+// memory partition before uploading the sketch and data!
+
+#include <LittleFS.h>
+#define FileSys LittleFS
+
+// Include the PNG decoder library
+#include <PNGdec.h>
+
+PNG png;
+#define MAX_IMAGE_WDITH 240 // Adjust for your images
+
+int16_t xpos = 0;
+int16_t ypos = 0;
+
+// Include the TFT library https://github.com/Bodmer/TFT_eSPI
+#include "SPI.h"
+#include <TFT_eSPI.h>              // Hardware-specific library
+TFT_eSPI tft = TFT_eSPI();         // Invoke custom library
+
+//====================================================================================
+//                                    Setup
+//====================================================================================
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println("\n\n Using the PNGdec library");
+
+  // Initialise FS
+  if (!FileSys.begin()) {
+    Serial.println("LittleFS initialisation failed!");
+    while (1) yield(); // Stay here twiddling thumbs waiting
+  }
+
+  // Initialise the TFT
+  tft.begin();
+  tft.fillScreen(TFT_BLACK);
+
+  Serial.println("\r\nInitialisation done.");
+}
+
+//====================================================================================
+//                                    Loop
+//====================================================================================
+void loop()
+{
+  // Scan LittleFS and load any *.png files
+  File root = LittleFS.open("/", "r");
+  while (File file = root.openNextFile()) {
+    String strname = file.name();
+    strname = "/" + strname;
+    Serial.println(file.name());
+    // If it is not a directory and filename ends in .png then load it
+    if (!file.isDirectory() && strname.endsWith(".png")) {
+      // Pass support callback function names to library
+      int16_t rc = png.open(strname.c_str(), pngOpen, pngClose, pngRead, pngSeek, pngDraw);
+      if (rc == PNG_SUCCESS) {
+        tft.startWrite();
+        Serial.printf("image specs: (%d x %d), %d bpp, pixel type: %d\n", png.getWidth(), png.getHeight(), png.getBpp(), png.getPixelType());
+        uint32_t dt = millis();
+        if (png.getWidth() > MAX_IMAGE_WDITH) {
+          Serial.println("Image too wide for allocated line buffer size!");
+        }
+        else {
+          rc = png.decode(NULL, 0);
+          png.close();
+        }
+        tft.endWrite();
+        // How long did rendering take...
+        Serial.print(millis()-dt); Serial.println("ms");
+      }
+    }
+    delay(3000);
+    tft.fillScreen(random(0x10000));
+  }
+}
+
+
+//=========================================v==========================================
+//                                      pngDraw
+//====================================================================================
+// This next function will be called during decoding of the png file to
+// render each image line to the TFT.  If you use a different TFT library
+// you will need to adapt this function to suit.
+// Callback function to draw pixels to the display
+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);
+}

examples/PNG Images/LittleFS_PNG/PNG_FS_Support.ino

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+// Here are the callback functions that the decPNG library
+// will use to open files, fetch data and close the file.
+
+File pngfile;
+
+void * pngOpen(const char *filename, int32_t *size) {
+  Serial.printf("Attempting to open %s\n", filename);
+  pngfile = FileSys.open(filename, "r");
+  *size = pngfile.size();
+  return &pngfile;
+}
+
+void pngClose(void *handle) {
+  File pngfile = *((File*)handle);
+  if (pngfile) pngfile.close();
+}
+
+int32_t pngRead(PNGFILE *page, uint8_t *buffer, int32_t length) {
+  if (!pngfile) return 0;
+  page = page; // Avoid warning
+  return pngfile.read(buffer, length);
+}
+
+int32_t pngSeek(PNGFILE *page, int32_t position) {
+  if (!pngfile) return 0;
+  page = page; // Avoid warning
+  return pngfile.seek(position);
+}

examples/PNG Images/LittleFS_PNG_DMA/LittleFS_PNG_DMA.ino

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+
+// This example if for processors with LittleFS capability (e.g. RP2040,
+// ESP32, ESP8266). It renders a png file that is stored in LittleFS
+// using the PNGdec library (available via library manager).
+
+// It uses DMA to send image data to the TFT while the decoding takes
+// place. The processor and display combination must support DMA to
+// run this sketch! The decode time dominates so DMA is mainly an advantage
+// for slow display interface speeds.
+
+// The test image is in the sketch "data" folder (press Ctrl+K to see it).
+// You must upload the image to LittleFS using the Arduino IDE Tools Data
+// Upload menu option (you may need to install extra tools for that).
+
+// Don't forget to use the Arduino IDE Tools menu to allocate a LittleFS
+// memory partition before uploading the sketch and data!
+
+#include <LittleFS.h>
+#define FileSys LittleFS
+
+// Include the PNG decoder library
+#include <PNGdec.h>
+
+PNG png;
+#define MAX_IMAGE_WDITH 240 // Adjust for your images
+
+int16_t xpos = 0;
+int16_t ypos = 0;
+
+// Include the TFT library https://github.com/Bodmer/TFT_eSPI
+#include "SPI.h"
+#include <TFT_eSPI.h>              // Hardware-specific library
+TFT_eSPI tft = TFT_eSPI();         // Invoke custom library
+
+//====================================================================================
+//                                    Setup
+//====================================================================================
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println("\n\n Using the PNGdec library");
+
+  // Initialise FS
+  if (!FileSys.begin()) {
+    Serial.println("LittleFS initialisation failed!");
+    while (1) yield(); // Stay here twiddling thumbs waiting
+  }
+
+  // Initialise the TFT
+  tft.begin();
+  tft.fillScreen(TFT_BLACK);
+  tft.initDMA();
+
+  Serial.println("\r\nInitialisation done.");
+}
+
+//====================================================================================
+//                                    Loop
+//====================================================================================
+void loop()
+{
+  // Scan LittleFS and load any *.png files
+  File root = LittleFS.open("/", "r");
+  while (File file = root.openNextFile()) {
+    String strname = file.name();
+    strname = "/" + strname;
+    Serial.println(file.name());
+    // If it is not a directory and filename ends in .png then load it
+    if (!file.isDirectory() && strname.endsWith(".png")) {
+      // Pass support callback function names to library
+      int16_t rc = png.open(strname.c_str(), pngOpen, pngClose, pngRead, pngSeek, pngDraw);
+      if (rc == PNG_SUCCESS) {
+        tft.startWrite();
+        Serial.printf("image specs: (%d x %d), %d bpp, pixel type: %d\n", png.getWidth(), png.getHeight(), png.getBpp(), png.getPixelType());
+        uint32_t dt = millis();
+        if (png.getWidth() > MAX_IMAGE_WDITH) {
+          Serial.println("Image too wide for allocated lin buffer!");
+        }
+        else {
+          rc = png.decode(NULL, 0);
+          png.close();
+        }
+        tft.endWrite();
+        // How long did rendering take...
+        Serial.print(millis()-dt); Serial.println("ms");
+      }
+    }
+    delay(3000);
+    tft.fillScreen(random(0x10000));
+  }
+}
+
+
+//=========================================v==========================================
+//                                      pngDraw
+//====================================================================================
+// This next function will be called during decoding of the png file to
+// render each image line to the TFT.  If you use a different TFT library
+// you will need to adapt this function to suit.
+// Callback function to draw pixels to the display
+void pngDraw(PNGDRAW *pDraw) {
+  uint16_t lineBuffer[MAX_IMAGE_WDITH];
+  static uint16_t dmaBuffer[MAX_IMAGE_WDITH]; // static so buffer persists after fn exit
+
+  png.getLineAsRGB565(pDraw, lineBuffer, PNG_RGB565_BIG_ENDIAN, 0xffffffff);
+  tft.pushImageDMA(xpos, ypos + pDraw->y, pDraw->iWidth, 1, lineBuffer, dmaBuffer);
+}

examples/PNG Images/LittleFS_PNG_DMA/PNG_FS_Support.ino

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+// Here are the callback functions that the decPNG library
+// will use to open files, fetch data and close the file.
+
+File pngfile;
+
+void * pngOpen(const char *filename, int32_t *size) {
+  Serial.printf("Attempting to open %s\n", filename);
+  pngfile = FileSys.open(filename, "r");
+  *size = pngfile.size();
+  return &pngfile;
+}
+
+void pngClose(void *handle) {
+  File pngfile = *((File*)handle);
+  if (pngfile) pngfile.close();
+}
+
+int32_t pngRead(PNGFILE *page, uint8_t *buffer, int32_t length) {
+  if (!pngfile) return 0;
+  page = page; // Avoid warning
+  return pngfile.read(buffer, length);
+}
+
+int32_t pngSeek(PNGFILE *page, int32_t position) {
+  if (!pngfile) return 0;
+  page = page; // Avoid warning
+  return pngfile.seek(position);
+}