Reorganize code into library for reuse

lib/image.c

@@ -0,0 +1,152 @@
+#include <assert.h>
+#include <setjmp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <png.h>
+#include <string.h>
+#include <mazemaker.h>
+#include "grid.h"
+
+#define LINE_THICKNESS 3
+#define BLOCK_SIZE 32
+#define MARGIN 20
+
+typedef struct {
+    char* data;
+    int w, h;
+} img_data_t;
+
+static void setPixel(img_data_t* img, int x, int y, char v) {
+    //fprintf(stderr, "setPixel(img, %d, %d, %d)\n", x, y, v);
+    assert((x < img->w) && (y < img->h));
+    img->data[y * img->w + x] = v;
+}
+
+static void setBox(img_data_t* img, int x, int y, int w, int h, char v) {
+    //fprintf(stderr, "setBox(img, %d, %d, %d, %d, %d)\n", x, y, w, h, v);
+    for (int i = 0; i < h; i++) {
+        for (int j = 0; j < w; j++) {
+            setPixel(img, x + j, y + i, v);
+        }
+    }
+}
+
+static img_data_t* gridToImageData(mazegrid_t const* g) {
+    img_data_t* result = malloc(sizeof(img_data_t));
+    result->w  = LINE_THICKNESS + g->width  * BLOCK_SIZE + 2 * MARGIN;
+    result->h = LINE_THICKNESS + g->height * BLOCK_SIZE + 2 * MARGIN;
+    result->data = malloc(result->w * result->h);
+    //fprintf(stderr, "Box dimensions: %d x %d\n", result->w, result->h);
+
+    // white background
+    memset(result->data, 0, result->w * result->h);
+
+    // draw basic outline
+    setBox(result, MARGIN, MARGIN, result->w - 2 * MARGIN, LINE_THICKNESS, 1);
+    setBox(result, MARGIN, MARGIN + LINE_THICKNESS, LINE_THICKNESS, (g->height - 1) * BLOCK_SIZE, 1);
+    setBox(result, MARGIN, result->h - MARGIN - 1 - LINE_THICKNESS, result->w - 2 * MARGIN, LINE_THICKNESS, 1);
+    setBox(result, result->w - MARGIN - LINE_THICKNESS, MARGIN + LINE_THICKNESS + BLOCK_SIZE, LINE_THICKNESS, (g->height - 1) * BLOCK_SIZE, 1);
+
+    // partitions
+    for (int i = 0; i < g->height; i++) {
+        for (int j = 0; j < g->width; j++) {
+            //fprintf(stderr, "Drawing (%d, %d) -> %d, %d\n", j, i, mazegrid_get_edge(g, j, i, EDGE_UP), mazegrid_get_edge(g, j, i, EDGE_RIGHT));
+            int x = MARGIN + LINE_THICKNESS + BLOCK_SIZE * j, y = result->h - MARGIN - LINE_THICKNESS - BLOCK_SIZE * i;
+            if (i < g->height - 1) {
+                if (mazegrid_get_edge(g, j, i, EDGE_UP) == 0)
+                    setBox(result, x - LINE_THICKNESS, y - BLOCK_SIZE, BLOCK_SIZE + LINE_THICKNESS, LINE_THICKNESS, 1);
+            }
+            if (j < g->width - 1) {
+                if (mazegrid_get_edge(g, j, i, EDGE_RIGHT) == 0)
+                    setBox(result, x + BLOCK_SIZE - LINE_THICKNESS, y - BLOCK_SIZE, LINE_THICKNESS, BLOCK_SIZE, 1);
+            }
+        }
+    }
+
+    return result;
+}
+
+static void writeImageData(img_data_t const* img, png_structp png_ptr) {
+    for (int i = 0; i < img->h; i++) {
+        png_byte row[3 * img->w];
+        for (int j = 0; j < img->w; j++) {
+            if (img->data[i * img->w + j]) {
+                // black
+                row[3 * j] = row[3 * j + 1] = row[3 * j + 2] = 0;
+            } else {
+                // white
+                row[3 * j] = row[3 * j + 1] = row[3 * j + 2] = 255;
+            }
+        }
+        png_write_row(png_ptr, row);
+    }
+}
+
+static void freeImageData(img_data_t* img) {
+    free(img->data);
+    free(img);
+}
+
+int mazemaker_maze_to_png(mazegrid_t const* g, char const* filename) {
+    int code = 1;
+    img_data_t* img = gridToImageData(g);
+    FILE *f = NULL;
+    png_structp png_ptr = NULL;
+    png_infop info_ptr  = NULL;
+    
+    if (strcmp(filename, "-") == 0) {
+        f = stdout;
+    } else {
+        f = fopen(filename, "wb");
+        if (NULL == f) {
+            fprintf(stderr, "Could not open %s for writing.\n", filename);
+            code = 0;
+            goto exit;
+        }
+    }
+
+    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+    if (png_ptr == NULL) {
+        fprintf(stderr, "Could not allocate PNG write struct.\n");
+        code = 0;
+        goto exit;
+    }
+
+    info_ptr = png_create_info_struct(png_ptr);
+    if (info_ptr == NULL) {
+        fprintf(stderr, "Could not allocate PNG info struct.\n");
+        code = 0;
+        goto exit;
+    }
+
+    if (setjmp(png_jmpbuf(png_ptr))) {
+        fprintf(stderr, "Error during PNG creation.\n");
+        code = 0;
+        goto exit;
+    }
+
+    png_init_io(png_ptr, f);
+
+    // Write header (8 bit color depth)
+    png_set_IHDR(png_ptr, info_ptr, img->w, img->h,
+                 8, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
+                 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+    png_write_info(png_ptr, info_ptr);
+
+    writeImageData(img, png_ptr);
+
+    png_write_end(png_ptr, NULL);
+
+exit:
+    if (strcmp(filename, "-") != 0) {
+        if (f != NULL) fclose(f);
+    }
+	if (info_ptr != NULL) {
+        png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
+        png_destroy_info_struct(png_ptr, &info_ptr);
+    }
+    if (png_ptr != NULL) png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
+    if (img != NULL) freeImageData(img);
+    return code;
+}