minui/resources.cpp - platform/bootable/recovery - Git at Google

 /*
  * Copyright (C) 2007 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>

 #include <fcntl.h>
 #include <stdio.h>

 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <sys/types.h>

 #include <linux/fb.h>
 #include <linux/kd.h>

 #include <png.h>

 #include "minui.h"

 #define SURFACE_DATA_ALIGNMENT 8

 static GRSurface* malloc_surface(size_t data_size) {
     size_t size = sizeof(GRSurface) + data_size + SURFACE_DATA_ALIGNMENT;
     unsigned char* temp = reinterpret_cast<unsigned char*>(malloc(size));
     if (temp == NULL) return NULL;
     GRSurface* surface = reinterpret_cast<GRSurface*>(temp);
     surface->data = temp + sizeof(GRSurface) +
         (SURFACE_DATA_ALIGNMENT - (sizeof(GRSurface) % SURFACE_DATA_ALIGNMENT));
     return surface;
 }

 static int open_png(const char* name, png_structp* png_ptr, png_infop* info_ptr,
                     png_uint_32* width, png_uint_32* height, png_byte* channels) {
     char resPath[256];
     unsigned char header[8];
     int result = 0;
     int color_type, bit_depth;
     size_t bytesRead;

     snprintf(resPath, sizeof(resPath)-1, "/res/images/%s.png", name);
     resPath[sizeof(resPath)-1] = '\0';
     FILE* fp = fopen(resPath, "rb");
     if (fp == NULL) {
         result = -1;
         goto exit;
     }

     bytesRead = fread(header, 1, sizeof(header), fp);
     if (bytesRead != sizeof(header)) {
         result = -2;
         goto exit;
     }

     if (png_sig_cmp(header, 0, sizeof(header))) {
         result = -3;
         goto exit;
     }

     *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
     if (!*png_ptr) {
         result = -4;
         goto exit;
     }

     *info_ptr = png_create_info_struct(*png_ptr);
     if (!*info_ptr) {
         result = -5;
         goto exit;
     }

     if (setjmp(png_jmpbuf(*png_ptr))) {
         result = -6;
         goto exit;
     }

     png_init_io(*png_ptr, fp);
     png_set_sig_bytes(*png_ptr, sizeof(header));
     png_read_info(*png_ptr, *info_ptr);

     png_get_IHDR(*png_ptr, *info_ptr, width, height, &bit_depth,
             &color_type, NULL, NULL, NULL);

     *channels = png_get_channels(*png_ptr, *info_ptr);

     if (bit_depth == 8 && *channels == 3 && color_type == PNG_COLOR_TYPE_RGB) {
         // 8-bit RGB images: great, nothing to do.
     } else if (bit_depth <= 8 && *channels == 1 && color_type == PNG_COLOR_TYPE_GRAY) {
         // 1-, 2-, 4-, or 8-bit gray images: expand to 8-bit gray.
         png_set_expand_gray_1_2_4_to_8(*png_ptr);
     } else if (bit_depth <= 8 && *channels == 1 && color_type == PNG_COLOR_TYPE_PALETTE) {
         // paletted images: expand to 8-bit RGB.  Note that we DON'T
         // currently expand the tRNS chunk (if any) to an alpha
         // channel, because minui doesn't support alpha channels in
         // general.
         png_set_palette_to_rgb(*png_ptr);
         *channels = 3;
     } else {
         fprintf(stderr, "minui doesn't support PNG depth %d channels %d color_type %d\n",
                 bit_depth, *channels, color_type);
         result = -7;
         goto exit;
     }

     return result;

   exit:
     if (result < 0) {
         png_destroy_read_struct(png_ptr, info_ptr, NULL);
     }
     if (fp != NULL) {
         fclose(fp);
     }

     return result;
 }

 // "display" surfaces are transformed into the framebuffer's required
 // pixel format (currently only RGBX is supported) at load time, so
 // gr_blit() can be nothing more than a memcpy() for each row.  The
 // next two functions are the only ones that know anything about the
 // framebuffer pixel format; they need to be modified if the
 // framebuffer format changes (but nothing else should).

 // Allocate and return a GRSurface* sufficient for storing an image of
 // the indicated size in the framebuffer pixel format.
 static GRSurface* init_display_surface(png_uint_32 width, png_uint_32 height) {
     GRSurface* surface = malloc_surface(width * height * 4);
     if (surface == NULL) return NULL;

     surface->width = width;
     surface->height = height;
     surface->row_bytes = width * 4;
     surface->pixel_bytes = 4;

     return surface;
 }

 // Copy 'input_row' to 'output_row', transforming it to the
 // framebuffer pixel format.  The input format depends on the value of
 // 'channels':
 //
 //   1 - input is 8-bit grayscale
 //   3 - input is 24-bit RGB
 //   4 - input is 32-bit RGBA/RGBX
 //
 // 'width' is the number of pixels in the row.
 static void transform_rgb_to_draw(unsigned char* input_row,
                                   unsigned char* output_row,
                                   int channels, int width) {
     int x;
     unsigned char* ip = input_row;
     unsigned char* op = output_row;

     switch (channels) {
         case 1:
             // expand gray level to RGBX
             for (x = 0; x < width; ++x) {
                 *op++ = *ip;
                 *op++ = *ip;
                 *op++ = *ip;
                 *op++ = 0xff;
                 ip++;
             }
             break;

         case 3:
             // expand RGBA to RGBX
             for (x = 0; x < width; ++x) {
                 *op++ = *ip++;
                 *op++ = *ip++;
                 *op++ = *ip++;
                 *op++ = 0xff;
             }
             break;

         case 4:
             // copy RGBA to RGBX
             memcpy(output_row, input_row, width*4);
             break;
     }
 }

 int res_create_display_surface(const char* name, GRSurface** pSurface) {
     GRSurface* surface = NULL;
     int result = 0;
     png_structp png_ptr = NULL;
     png_infop info_ptr = NULL;
     png_uint_32 width, height;
     png_byte channels;
     unsigned char* p_row;
     unsigned int y;

     *pSurface = NULL;

     result = open_png(name, &png_ptr, &info_ptr, &width, &height, &channels);
     if (result < 0) return result;

     surface = init_display_surface(width, height);
     if (surface == NULL) {
         result = -8;
         goto exit;
     }

 #if defined(RECOVERY_ABGR) || defined(RECOVERY_BGRA)
     png_set_bgr(png_ptr);
 #endif

     p_row = reinterpret_cast<unsigned char*>(malloc(width * 4));
     for (y = 0; y < height; ++y) {
         png_read_row(png_ptr, p_row, NULL);
         transform_rgb_to_draw(p_row, surface->data + y * surface->row_bytes, channels, width);
     }
     free(p_row);

     *pSurface = surface;

   exit:
     png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
     if (result < 0 && surface != NULL) free(surface);
     return result;
 }

 int res_create_multi_display_surface(const char* name, int* frames, int* fps,
         GRSurface*** pSurface) {
     GRSurface** surface = NULL;
     int result = 0;
     png_structp png_ptr = NULL;
     png_infop info_ptr = NULL;
     png_uint_32 width, height;
     png_byte channels;
     png_textp text;
     int num_text;
     unsigned char* p_row;
     unsigned int y;

     *pSurface = NULL;
     *frames = -1;

     result = open_png(name, &png_ptr, &info_ptr, &width, &height, &channels);
     if (result < 0) return result;

     *frames = 1;
     *fps = 20;
     if (png_get_text(png_ptr, info_ptr, &text, &num_text)) {
         for (int i = 0; i < num_text; ++i) {
             if (text[i].key && strcmp(text[i].key, "Frames") == 0 && text[i].text) {
                 *frames = atoi(text[i].text);
             } else if (text[i].key && strcmp(text[i].key, "FPS") == 0 && text[i].text) {
                 *fps = atoi(text[i].text);
             }
         }
         printf("  found frames = %d\n", *frames);
         printf("  found fps = %d\n", *fps);
     }

     if (frames <= 0 || fps <= 0) {
         printf("bad number of frames (%d) and/or FPS (%d)\n", *frames, *fps);
         result = -10;
         goto exit;
     }

     if (height % *frames != 0) {
         printf("bad height (%d) for frame count (%d)\n", height, *frames);
         result = -9;
         goto exit;
     }

     surface = reinterpret_cast<GRSurface**>(malloc(*frames * sizeof(GRSurface*)));
     if (surface == NULL) {
         result = -8;
         goto exit;
     }
     for (int i = 0; i < *frames; ++i) {
         surface[i] = init_display_surface(width, height / *frames);
         if (surface[i] == NULL) {
             result = -8;
             goto exit;
         }
     }

 #if defined(RECOVERY_ABGR) || defined(RECOVERY_BGRA)
     png_set_bgr(png_ptr);
 #endif

     p_row = reinterpret_cast<unsigned char*>(malloc(width * 4));
     for (y = 0; y < height; ++y) {
         png_read_row(png_ptr, p_row, NULL);
         int frame = y % *frames;
         unsigned char* out_row = surface[frame]->data +
             (y / *frames) * surface[frame]->row_bytes;
         transform_rgb_to_draw(p_row, out_row, channels, width);
     }
     free(p_row);

     *pSurface = reinterpret_cast<GRSurface**>(surface);

 exit:
     png_destroy_read_struct(&png_ptr, &info_ptr, NULL);

     if (result < 0) {
         if (surface) {
             for (int i = 0; i < *frames; ++i) {
                 if (surface[i]) free(surface[i]);
             }
             free(surface);
         }
     }
     return result;
 }

 int res_create_alpha_surface(const char* name, GRSurface** pSurface) {
     GRSurface* surface = NULL;
     int result = 0;
     png_structp png_ptr = NULL;
     png_infop info_ptr = NULL;
     png_uint_32 width, height;
     png_byte channels;

     *pSurface = NULL;

     result = open_png(name, &png_ptr, &info_ptr, &width, &height, &channels);
     if (result < 0) return result;

     if (channels != 1) {
         result = -7;
         goto exit;
     }

     surface = malloc_surface(width * height);
     if (surface == NULL) {
         result = -8;
         goto exit;
     }
     surface->width = width;
     surface->height = height;
     surface->row_bytes = width;
     surface->pixel_bytes = 1;

 #if defined(RECOVERY_ABGR) || defined(RECOVERY_BGRA)
     png_set_bgr(png_ptr);
 #endif

     unsigned char* p_row;
     unsigned int y;
     for (y = 0; y < height; ++y) {
         p_row = surface->data + y * surface->row_bytes;
         png_read_row(png_ptr, p_row, NULL);
     }

     *pSurface = surface;

   exit:
     png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
     if (result < 0 && surface != NULL) free(surface);
     return result;
 }

 // This function tests if a locale string stored in PNG (prefix) matches
 // the locale string provided by the system (locale).
 bool matches_locale(const char* prefix, const char* locale) {
     if (locale == NULL) return false;

     // Return true if the whole string of prefix matches the top part of
     // locale. For instance, prefix == "en" matches locale == "en_US";
     // and prefix == "zh_CN" matches locale == "zh_CN_#Hans".

     return (strncmp(prefix, locale, strlen(prefix)) == 0);
 }

 int res_create_localized_alpha_surface(const char* name,
                                        const char* locale,
                                        GRSurface** pSurface) {
     GRSurface* surface = NULL;
     int result = 0;
     png_structp png_ptr = NULL;
     png_infop info_ptr = NULL;
     png_uint_32 width, height;
     png_byte channels;
     unsigned char* row;
     png_uint_32 y;

     *pSurface = NULL;

     if (locale == NULL) {
         surface = malloc_surface(0);
         surface->width = 0;
         surface->height = 0;
         surface->row_bytes = 0;
         surface->pixel_bytes = 1;
         goto exit;
     }

     result = open_png(name, &png_ptr, &info_ptr, &width, &height, &channels);
     if (result < 0) return result;

     if (channels != 1) {
         result = -7;
         goto exit;
     }

     row = reinterpret_cast<unsigned char*>(malloc(width));
     for (y = 0; y < height; ++y) {
         png_read_row(png_ptr, row, NULL);
         int w = (row[1] << 8) | row[0];
         int h = (row[3] << 8) | row[2];
         int len = row[4];
         char* loc = (char*)row+5;

         if (y+1+h >= height || matches_locale(loc, locale)) {
             printf("  %20s: %s (%d x %d @ %d)\n", name, loc, w, h, y);

             surface = malloc_surface(w*h);
             if (surface == NULL) {
                 result = -8;
                 goto exit;
             }
             surface->width = w;
             surface->height = h;
             surface->row_bytes = w;
             surface->pixel_bytes = 1;

             int i;
             for (i = 0; i < h; ++i, ++y) {
                 png_read_row(png_ptr, row, NULL);
                 memcpy(surface->data + i*w, row, w);
             }

             *pSurface = reinterpret_cast<GRSurface*>(surface);
             break;
         } else {
             int i;
             for (i = 0; i < h; ++i, ++y) {
                 png_read_row(png_ptr, row, NULL);
             }
         }
     }

 exit:
     png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
     if (result < 0 && surface != NULL) free(surface);
     return result;
 }

 void res_free_surface(GRSurface* surface) {
     free(surface);
 }
	/*
	* Copyright (C) 2007 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include <stdlib.h>
	#include <string.h>
	#include <unistd.h>

	#include <fcntl.h>
	#include <stdio.h>

	#include <sys/ioctl.h>
	#include <sys/mman.h>
	#include <sys/types.h>

	#include <linux/fb.h>
	#include <linux/kd.h>

	#include <png.h>

	#include "minui.h"

	#define SURFACE_DATA_ALIGNMENT 8

	static GRSurface* malloc_surface(size_t data_size) {
	size_t size = sizeof(GRSurface) + data_size + SURFACE_DATA_ALIGNMENT;
	unsigned char* temp = reinterpret_cast<unsigned char*>(malloc(size));
	if (temp == NULL) return NULL;
	GRSurface* surface = reinterpret_cast<GRSurface*>(temp);
	surface->data = temp + sizeof(GRSurface) +
	(SURFACE_DATA_ALIGNMENT - (sizeof(GRSurface) % SURFACE_DATA_ALIGNMENT));
	return surface;
	}

	static int open_png(const char* name, png_structp* png_ptr, png_infop* info_ptr,
	png_uint_32* width, png_uint_32* height, png_byte* channels) {
	char resPath[256];
	unsigned char header[8];
	int result = 0;
	int color_type, bit_depth;
	size_t bytesRead;

	snprintf(resPath, sizeof(resPath)-1, "/res/images/%s.png", name);
	resPath[sizeof(resPath)-1] = '\0';
	FILE* fp = fopen(resPath, "rb");
	if (fp == NULL) {
	result = -1;
	goto exit;
	}

	bytesRead = fread(header, 1, sizeof(header), fp);
	if (bytesRead != sizeof(header)) {
	result = -2;
	goto exit;
	}

	if (png_sig_cmp(header, 0, sizeof(header))) {
	result = -3;
	goto exit;
	}

	*png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!*png_ptr) {
	result = -4;
	goto exit;
	}

	info_ptr = png_create_info_struct(png_ptr);
	if (!*info_ptr) {
	result = -5;
	goto exit;
	}

	if (setjmp(png_jmpbuf(*png_ptr))) {
	result = -6;
	goto exit;
	}

	png_init_io(*png_ptr, fp);
	png_set_sig_bytes(*png_ptr, sizeof(header));
	png_read_info(png_ptr, info_ptr);

	png_get_IHDR(png_ptr, info_ptr, width, height, &bit_depth,
	&color_type, NULL, NULL, NULL);

	channels = png_get_channels(png_ptr, *info_ptr);

	if (bit_depth == 8 && *channels == 3 && color_type == PNG_COLOR_TYPE_RGB) {
	// 8-bit RGB images: great, nothing to do.
	} else if (bit_depth <= 8 && *channels == 1 && color_type == PNG_COLOR_TYPE_GRAY) {
	// 1-, 2-, 4-, or 8-bit gray images: expand to 8-bit gray.
	png_set_expand_gray_1_2_4_to_8(*png_ptr);
	} else if (bit_depth <= 8 && *channels == 1 && color_type == PNG_COLOR_TYPE_PALETTE) {
	// paletted images: expand to 8-bit RGB. Note that we DON'T
	// currently expand the tRNS chunk (if any) to an alpha
	// channel, because minui doesn't support alpha channels in
	// general.
	png_set_palette_to_rgb(*png_ptr);
	*channels = 3;
	} else {
	fprintf(stderr, "minui doesn't support PNG depth %d channels %d color_type %d\n",
	bit_depth, *channels, color_type);
	result = -7;
	goto exit;
	}

	return result;

	exit:
	if (result < 0) {
	png_destroy_read_struct(png_ptr, info_ptr, NULL);
	}
	if (fp != NULL) {
	fclose(fp);
	}

	return result;
	}

	// "display" surfaces are transformed into the framebuffer's required
	// pixel format (currently only RGBX is supported) at load time, so
	// gr_blit() can be nothing more than a memcpy() for each row. The
	// next two functions are the only ones that know anything about the
	// framebuffer pixel format; they need to be modified if the
	// framebuffer format changes (but nothing else should).

	// Allocate and return a GRSurface* sufficient for storing an image of
	// the indicated size in the framebuffer pixel format.
	static GRSurface* init_display_surface(png_uint_32 width, png_uint_32 height) {
	GRSurface* surface = malloc_surface(width * height * 4);
	if (surface == NULL) return NULL;

	surface->width = width;
	surface->height = height;
	surface->row_bytes = width * 4;
	surface->pixel_bytes = 4;

	return surface;
	}

	// Copy 'input_row' to 'output_row', transforming it to the
	// framebuffer pixel format. The input format depends on the value of
	// 'channels':
	//
	// 1 - input is 8-bit grayscale
	// 3 - input is 24-bit RGB
	// 4 - input is 32-bit RGBA/RGBX
	//
	// 'width' is the number of pixels in the row.
	static void transform_rgb_to_draw(unsigned char* input_row,
	unsigned char* output_row,
	int channels, int width) {
	int x;
	unsigned char* ip = input_row;
	unsigned char* op = output_row;

	switch (channels) {
	case 1:
	// expand gray level to RGBX
	for (x = 0; x < width; ++x) {
	op++ = ip;
	op++ = ip;
	op++ = ip;
	*op++ = 0xff;
	ip++;
	}
	break;

	case 3:
	// expand RGBA to RGBX
	for (x = 0; x < width; ++x) {
	op++ = ip++;
	op++ = ip++;
	op++ = ip++;
	*op++ = 0xff;
	}
	break;

	case 4:
	// copy RGBA to RGBX
	memcpy(output_row, input_row, width*4);
	break;
	}
	}

	int res_create_display_surface(const char* name, GRSurface** pSurface) {
	GRSurface* surface = NULL;
	int result = 0;
	png_structp png_ptr = NULL;
	png_infop info_ptr = NULL;
	png_uint_32 width, height;
	png_byte channels;
	unsigned char* p_row;
	unsigned int y;

	*pSurface = NULL;

	result = open_png(name, &png_ptr, &info_ptr, &width, &height, &channels);
	if (result < 0) return result;

	surface = init_display_surface(width, height);
	if (surface == NULL) {
	result = -8;
	goto exit;
	}

	#if defined(RECOVERY_ABGR) \|\| defined(RECOVERY_BGRA)
	png_set_bgr(png_ptr);
	#endif

	p_row = reinterpret_cast<unsigned char>(malloc(width 4));
	for (y = 0; y < height; ++y) {
	png_read_row(png_ptr, p_row, NULL);
	transform_rgb_to_draw(p_row, surface->data + y * surface->row_bytes, channels, width);
	}
	free(p_row);

	*pSurface = surface;

	exit:
	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
	if (result < 0 && surface != NULL) free(surface);
	return result;
	}

	int res_create_multi_display_surface(const char* name, int* frames, int* fps,
	GRSurface*** pSurface) {
	GRSurface** surface = NULL;
	int result = 0;
	png_structp png_ptr = NULL;
	png_infop info_ptr = NULL;
	png_uint_32 width, height;
	png_byte channels;
	png_textp text;
	int num_text;
	unsigned char* p_row;
	unsigned int y;

	*pSurface = NULL;
	*frames = -1;

	result = open_png(name, &png_ptr, &info_ptr, &width, &height, &channels);
	if (result < 0) return result;

	*frames = 1;
	*fps = 20;
	if (png_get_text(png_ptr, info_ptr, &text, &num_text)) {
	for (int i = 0; i < num_text; ++i) {
	if (text[i].key && strcmp(text[i].key, "Frames") == 0 && text[i].text) {
	*frames = atoi(text[i].text);
	} else if (text[i].key && strcmp(text[i].key, "FPS") == 0 && text[i].text) {
	*fps = atoi(text[i].text);
	}
	}
	printf(" found frames = %d\n", *frames);
	printf(" found fps = %d\n", *fps);
	}

	if (frames <= 0 \|\| fps <= 0) {
	printf("bad number of frames (%d) and/or FPS (%d)\n", frames, fps);
	result = -10;
	goto exit;
	}

	if (height % *frames != 0) {
	printf("bad height (%d) for frame count (%d)\n", height, *frames);
	result = -9;
	goto exit;
	}

	surface = reinterpret_cast<GRSurface*>(malloc(frames * sizeof(GRSurface*)));
	if (surface == NULL) {
	result = -8;
	goto exit;
	}
	for (int i = 0; i < *frames; ++i) {
	surface[i] = init_display_surface(width, height / *frames);
	if (surface[i] == NULL) {
	result = -8;
	goto exit;
	}
	}

	#if defined(RECOVERY_ABGR) \|\| defined(RECOVERY_BGRA)
	png_set_bgr(png_ptr);
	#endif

	p_row = reinterpret_cast<unsigned char>(malloc(width 4));
	for (y = 0; y < height; ++y) {
	png_read_row(png_ptr, p_row, NULL);
	int frame = y % *frames;
	unsigned char* out_row = surface[frame]->data +
	(y / frames) surface[frame]->row_bytes;
	transform_rgb_to_draw(p_row, out_row, channels, width);
	}
	free(p_row);

	pSurface = reinterpret_cast<GRSurface*>(surface);

	exit:
	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);

	if (result < 0) {
	if (surface) {
	for (int i = 0; i < *frames; ++i) {
	if (surface[i]) free(surface[i]);
	}
	free(surface);
	}
	}
	return result;
	}

	int res_create_alpha_surface(const char* name, GRSurface** pSurface) {
	GRSurface* surface = NULL;
	int result = 0;
	png_structp png_ptr = NULL;
	png_infop info_ptr = NULL;
	png_uint_32 width, height;
	png_byte channels;

	*pSurface = NULL;

	result = open_png(name, &png_ptr, &info_ptr, &width, &height, &channels);
	if (result < 0) return result;

	if (channels != 1) {
	result = -7;
	goto exit;
	}

	surface = malloc_surface(width * height);
	if (surface == NULL) {
	result = -8;
	goto exit;
	}
	surface->width = width;
	surface->height = height;
	surface->row_bytes = width;
	surface->pixel_bytes = 1;

	#if defined(RECOVERY_ABGR) \|\| defined(RECOVERY_BGRA)
	png_set_bgr(png_ptr);
	#endif

	unsigned char* p_row;
	unsigned int y;
	for (y = 0; y < height; ++y) {
	p_row = surface->data + y * surface->row_bytes;
	png_read_row(png_ptr, p_row, NULL);
	}

	*pSurface = surface;

	exit:
	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
	if (result < 0 && surface != NULL) free(surface);
	return result;
	}

	// This function tests if a locale string stored in PNG (prefix) matches
	// the locale string provided by the system (locale).
	bool matches_locale(const char* prefix, const char* locale) {
	if (locale == NULL) return false;

	// Return true if the whole string of prefix matches the top part of
	// locale. For instance, prefix == "en" matches locale == "en_US";
	// and prefix == "zh_CN" matches locale == "zh_CN_#Hans".

	return (strncmp(prefix, locale, strlen(prefix)) == 0);
	}

	int res_create_localized_alpha_surface(const char* name,
	const char* locale,
	GRSurface** pSurface) {
	GRSurface* surface = NULL;
	int result = 0;
	png_structp png_ptr = NULL;
	png_infop info_ptr = NULL;
	png_uint_32 width, height;
	png_byte channels;
	unsigned char* row;
	png_uint_32 y;

	*pSurface = NULL;

	if (locale == NULL) {
	surface = malloc_surface(0);
	surface->width = 0;
	surface->height = 0;
	surface->row_bytes = 0;
	surface->pixel_bytes = 1;
	goto exit;
	}

	result = open_png(name, &png_ptr, &info_ptr, &width, &height, &channels);
	if (result < 0) return result;

	if (channels != 1) {
	result = -7;
	goto exit;
	}

	row = reinterpret_cast<unsigned char*>(malloc(width));
	for (y = 0; y < height; ++y) {
	png_read_row(png_ptr, row, NULL);
	int w = (row[1] << 8) \| row[0];
	int h = (row[3] << 8) \| row[2];
	int len = row[4];
	char* loc = (char*)row+5;

	if (y+1+h >= height \|\| matches_locale(loc, locale)) {
	printf(" %20s: %s (%d x %d @ %d)\n", name, loc, w, h, y);

	surface = malloc_surface(w*h);
	if (surface == NULL) {
	result = -8;
	goto exit;
	}
	surface->width = w;
	surface->height = h;
	surface->row_bytes = w;
	surface->pixel_bytes = 1;

	int i;
	for (i = 0; i < h; ++i, ++y) {
	png_read_row(png_ptr, row, NULL);
	memcpy(surface->data + i*w, row, w);
	}

	pSurface = reinterpret_cast<GRSurface>(surface);
	break;
	} else {
	int i;
	for (i = 0; i < h; ++i, ++y) {
	png_read_row(png_ptr, row, NULL);
	}
	}
	}

	exit:
	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
	if (result < 0 && surface != NULL) free(surface);
	return result;
	}

	void res_free_surface(GRSurface* surface) {
	free(surface);
	}