X-Git-Url: https://git.notmuchmail.org/git?a=blobdiff_plain;f=image.cpp;h=1f96c29bb5c60c8d30d657e7a0c6ad7a09f1f3b0;hb=ecf37415b269e6051b01104740cb8f6ae736e8ad;hp=ce37c190c097cff6a624d4870e9dca5a58adfad3;hpb=4cebb746f86d7ff67d816e15a68921885c2958c9;p=apitrace

diff --git a/image.cpp b/image.cpp
index ce37c19..1f96c29 100644
--- a/image.cpp
+++ b/image.cpp
@@ -26,7 +26,9 @@
 
 #include <png.h>
 
+#include <math.h>
 #include <stdint.h>
+#include <stdlib.h>
 
 #include <fstream>
 
@@ -164,7 +166,7 @@ Image::writePNG(const char *filename) const {
     png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_RGB_ALPHA,
         PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
 
-    png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);
+    png_set_compression_level(png_ptr, Z_DEFAULT_COMPRESSION);
 
     png_write_info(png_ptr, info_ptr);
 
@@ -273,4 +275,150 @@ no_fp:
 }
 
 
+double Image::compare(Image &ref)
+{
+    if (width != ref.width ||
+        height != ref.height) {
+        return 0.0;
+    }
+
+    const unsigned char *pSrc = start();
+    const unsigned char *pRef = ref.start();
+
+    unsigned long long error = 0;
+    for (unsigned y = 0; y < height; ++y) {
+        for (unsigned  x = 0; x < width; ++x) {
+            // FIXME: Ignore alpha channel until we are able to pick a visual
+            // that matches the traces
+            for (unsigned  c = 0; c < 3; ++c) {
+                int delta = pSrc[x*4 + c] - pRef[x*4 + c];
+                error += delta*delta;
+            }
+        }
+
+        pSrc += stride();
+        pRef += ref.stride();
+    }
+
+    double numerator = error*2 + 1;
+    double denominator = height*width*3ULL*255ULL*255ULL*2;
+    double quotient = numerator/denominator;
+
+    // Precision in bits
+    double precision = -log(quotient)/log(2.0);
+
+    return precision;
+}
+
+struct png_tmp_buffer
+{
+    char *buffer;
+    size_t size;
+};
+
+static void
+pngWriteCallback(png_structp png_ptr, png_bytep data, png_size_t length)
+{
+    struct png_tmp_buffer *buf = (struct png_tmp_buffer*) png_ptr->io_ptr;
+    size_t nsize = buf->size + length;
+
+    /* allocate or grow buffer */
+    if (buf->buffer)
+        buf->buffer = (char*)realloc(buf->buffer, nsize);
+    else
+        buf->buffer = (char*)malloc(nsize);
+
+    if (!buf->buffer)
+        png_error(png_ptr, "Buffer allocation error");
+
+    memcpy(buf->buffer + buf->size, data, length);
+    buf->size += length;
+}
+
+bool writePixelsToBuffer(unsigned char *pixels,
+                         unsigned width, unsigned height, unsigned numChannels,
+                         bool flipped,
+                         char **buffer,
+                         int *size)
+{
+    struct png_tmp_buffer png_mem;
+    png_structp png_ptr;
+    png_infop info_ptr;
+    int type;
+
+    png_mem.buffer = NULL;
+    png_mem.size = 0;
+
+    switch (numChannels) {
+    case 4:
+        type = PNG_COLOR_TYPE_RGB_ALPHA;
+        break;
+    case 3:
+        type = PNG_COLOR_TYPE_RGB;
+        break;
+    case 2:
+        type = PNG_COLOR_TYPE_GRAY_ALPHA;
+        break;
+    case 1:
+        type = PNG_COLOR_TYPE_GRAY;
+        break;
+    default:
+        goto no_png;
+    }
+
+    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+    if (!png_ptr)
+        goto no_png;
+
+    info_ptr = png_create_info_struct(png_ptr);
+    if (!info_ptr) {
+        png_destroy_write_struct(&png_ptr,  NULL);
+        goto no_png;
+    }
+
+    if (setjmp(png_jmpbuf(png_ptr))) {
+        png_destroy_write_struct(&png_ptr, &info_ptr);
+        goto no_png;
+    }
+
+    png_set_write_fn(png_ptr, &png_mem, pngWriteCallback, NULL);
+
+    png_set_IHDR(png_ptr, info_ptr, width, height, 8,
+                 type, PNG_INTERLACE_NONE,
+                 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+    png_set_compression_level(png_ptr, Z_DEFAULT_COMPRESSION);
+
+    png_write_info(png_ptr, info_ptr);
+
+    if (!flipped) {
+        for (unsigned y = 0; y < height; ++y) {
+            png_bytep row = (png_bytep)(pixels + y*width*numChannels);
+            png_write_rows(png_ptr, &row, 1);
+        }
+    } else {
+        unsigned y = height;
+        while (y--) {
+            png_bytep row = (png_bytep)(pixels + y*width*numChannels);
+            png_write_rows(png_ptr, &row, 1);
+        }
+    }
+
+    png_write_end(png_ptr, info_ptr);
+    png_destroy_write_struct(&png_ptr, &info_ptr);
+
+    *buffer = png_mem.buffer;
+    *size = png_mem.size;
+
+    return true;
+
+no_png:
+    *buffer = NULL;
+    *size = 0;
+
+    if (png_mem.buffer)
+        free(png_mem.buffer);
+    return false;
+}
+
 } /* namespace Image */