Add ktx

2026-06-14 19:09:18 +01:00
parent 14bd1a9271
commit 13fa90a0e9
3958 changed files with 999286 additions and 4 deletions
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+/*
+LodePNG Examples
+
+Copyright (c) 2005-2010 Lode Vandevenne
+
+This software is provided 'as-is', without any express or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+    1. The origin of this software must not be misrepresented; you must not
+    claim that you wrote the original software. If you use this software
+    in a product, an acknowledgment in the product documentation would be
+    appreciated but is not required.
+
+    2. Altered source versions must be plainly marked as such, and must not be
+    misrepresented as being the original software.
+
+    3. This notice may not be removed or altered from any source
+    distribution.
+*/
+
+/*
+Load a BMP image and convert it to a PNG image. This example also shows how
+to use other data with the same memory structure as BMP, such as the image
+format native to win32, GDI (HBITMAP, BITMAPINFO, ...) often encountered if
+you're programming for Windows in Visual Studio.
+
+This example only supports uncompressed 24-bit RGB or 32-bit RGBA bitmaps.
+For other types of BMP's, use a full fledged BMP decoder, or convert the
+bitmap to 24-bit or 32-bit format.
+
+NOTE: it overwrites the output file without warning if it exists!
+*/
+
+//g++ lodepng.cpp example_bmp2png.cpp -ansi -pedantic -Wall -Wextra -O3
+
+#include "lodepng.h"
+
+#include <iostream>
+
+//returns 0 if all went ok, non-0 if error
+//output image is always given in RGBA (with alpha channel), even if it's a BMP without alpha channel
+unsigned decodeBMP(std::vector<unsigned char>& image, unsigned& w, unsigned& h, const std::vector<unsigned char>& bmp) {
+  static const unsigned MINHEADER = 54; //minimum BMP header size
+
+  if(bmp.size() < MINHEADER) return -1;
+  if(bmp[0] != 'B' || bmp[1] != 'M') return 1; //It's not a BMP file if it doesn't start with marker 'BM'
+  unsigned pixeloffset = bmp[10] + 256 * bmp[11]; //where the pixel data starts
+  //read width and height from BMP header
+  w = bmp[18] + bmp[19] * 256;
+  h = bmp[22] + bmp[23] * 256;
+  //read number of channels from BMP header
+  if(bmp[28] != 24 && bmp[28] != 32) return 2; //only 24-bit and 32-bit BMPs are supported.
+  unsigned numChannels = bmp[28] / 8;
+
+  //The amount of scanline bytes is width of image times channels, with extra bytes added if needed
+  //to make it a multiple of 4 bytes.
+  unsigned scanlineBytes = w * numChannels;
+  if(scanlineBytes % 4 != 0) scanlineBytes = (scanlineBytes / 4) * 4 + 4;
+
+  unsigned dataSize = scanlineBytes * h;
+  if(bmp.size() < dataSize + pixeloffset) return 3; //BMP file too small to contain all pixels
+
+  image.resize(w * h * 4);
+
+  /*
+  There are 3 differences between BMP and the raw image buffer for LodePNG:
+  -it's upside down
+  -it's in BGR instead of RGB format (or BRGA instead of RGBA)
+  -each scanline has padding bytes to make it a multiple of 4 if needed
+  The 2D for loop below does all these 3 conversions at once.
+  */
+  for(unsigned y = 0; y < h; y++)
+  for(unsigned x = 0; x < w; x++) {
+    //pixel start byte position in the BMP
+    unsigned bmpos = pixeloffset + (h - y - 1) * scanlineBytes + numChannels * x;
+    //pixel start byte position in the new raw image
+    unsigned newpos = 4 * y * w + 4 * x;
+    if(numChannels == 3) {
+      image[newpos + 0] = bmp[bmpos + 2]; //R
+      image[newpos + 1] = bmp[bmpos + 1]; //G
+      image[newpos + 2] = bmp[bmpos + 0]; //B
+      image[newpos + 3] = 255;            //A
+    } else {
+      image[newpos + 0] = bmp[bmpos + 2]; //R
+      image[newpos + 1] = bmp[bmpos + 1]; //G
+      image[newpos + 2] = bmp[bmpos + 0]; //B
+      image[newpos + 3] = bmp[bmpos + 3]; //A
+    }
+  }
+  return 0;
+}
+
+int main(int argc, char *argv[]) {
+  if(argc < 3) {
+    std::cout << "Please provide input BMP and output PNG file names" << std::endl;
+    return 0;
+  }
+
+  std::vector<unsigned char> bmp;
+  lodepng::load_file(bmp, argv[1]);
+  std::vector<unsigned char> image;
+  unsigned w, h;
+  unsigned error = decodeBMP(image, w, h, bmp);
+
+  if(error) {
+    std::cout << "BMP decoding error " << error << std::endl;
+    return 0;
+  }
+
+  std::vector<unsigned char> png;
+  error = lodepng::encode(png, image, w, h);
+
+  if(error) {
+    std::cout << "PNG encoding error " << error << ": " << lodepng_error_text(error) << std::endl;
+    return 0;
+  }
+
+  lodepng::save_file(png, argv[2]);
+
+}