plus-messenger/TMessagesProj/jni/image.c

#include <jni.h>
#include <stdio.h>
#include <setjmp.h>
#include <libjpeg/jpeglib.h>
#include "utils.h"

typedef struct my_error_mgr {
    struct jpeg_error_mgr pub;
    jmp_buf setjmp_buffer;
} *my_error_ptr;


METHODDEF(void) my_error_exit(j_common_ptr cinfo) {
    my_error_ptr myerr = (my_error_ptr) cinfo->err;
    (*cinfo->err->output_message) (cinfo);
    longjmp(myerr->setjmp_buffer, 1);
}

JNIEXPORT void Java_org_telegram_messenger_Utilities_loadBitmap(JNIEnv *env, jclass class, jstring path, jintArray bitmap, int scale, int format, int width, int height) {
    
    int i;
    
    char *fileName = (*env)->GetStringUTFChars(env, path, NULL);
    FILE *infile;
    
    if ((infile = fopen(fileName, "rb"))) {
        struct my_error_mgr jerr;
        struct jpeg_decompress_struct cinfo;
        
        cinfo.err = jpeg_std_error(&jerr.pub);
        jerr.pub.error_exit = my_error_exit;
        
        if (!setjmp(jerr.setjmp_buffer)) {
            unsigned char *bitmapBuf = (*env)->GetPrimitiveArrayCritical(env, bitmap, 0);
            if (bitmapBuf) {
                jpeg_create_decompress(&cinfo);
                jpeg_stdio_src(&cinfo, infile);
                
                jpeg_read_header(&cinfo, TRUE);
                
                cinfo.scale_denom = scale;
                cinfo.scale_num = 1;
                
                jpeg_start_decompress(&cinfo);
                int row_stride = cinfo.output_width * cinfo.output_components;
                JSAMPARRAY buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);
                int stride = width;
                if (format == 0) {
                    stride *= 4;
                } else if (format == 1) {
                    stride *= 2;
                }

                unsigned char *pixels = bitmapBuf;

                int rowCount = min(cinfo.output_height, height);
                int colCount = min(cinfo.output_width, width);
                
                while (cinfo.output_scanline < rowCount) {
                    jpeg_read_scanlines(&cinfo, buffer, 1);
                    
                    if (format == 0) {
                        if (cinfo.out_color_space == JCS_GRAYSCALE) {
                            for (i = 0; i < colCount; i++) {
                                float alpha = buffer[0][i] / 255.0f;
                                pixels[i * 4] *= alpha;
                                pixels[i * 4 + 1] *= alpha;
                                pixels[i * 4 + 2] *= alpha;
                                pixels[i * 4 + 3] = buffer[0][i];
                            }
                        } else {
                            int c = 0;
                            for (i = 0; i < colCount; i++) {
                                pixels[i * 4] = buffer[0][i * 3 + 2];
                                pixels[i * 4 + 1] = buffer[0][i * 3 + 1];
                                pixels[i * 4 + 2] = buffer[0][i * 3];
                                pixels[i * 4 + 3] = 255;
                                c += 4;
                            }
                        }
                    } else if (format == 1) {
                        
                    }
                    
                    pixels += stride;
                }
                (*env)->ReleasePrimitiveArrayCritical(env, bitmap, bitmapBuf, 0);
                jpeg_finish_decompress(&cinfo);
            } else {
                throwException(env, "can't get bitmap buff");
            }
        } else {
            throwException(env, "the JPEG code has signaled an error");
        }
        
        jpeg_destroy_decompress(&cinfo);
        fclose(infile);
    } else {
        throwException(env, "can't open %s", fileName);
    }
    
    (*env)->ReleaseStringUTFChars(env, path, fileName);
}