jpg_loader: code refactoring

keep it clean and neat code add some TODO comments for the future tasks.

This also fixes potential data memory leak.

src/loaders/jpg/tvgJpgLoader.cpp

@@ -21,6 +21,7 @@
  */
 
 #include <memory.h>
+#include <turbojpeg.h>
 #include "tvgLoaderMgr.h"
 #include "tvgJpgLoader.h"
 
@@ -30,10 +31,10 @@
 
 void JpgLoader::clear()
 {
-    tjFree(data);
-    data = NULL;
-    pointer = NULL;
+    if (freeData) free(data);
+    data = nullptr;
     size = 0;
+    freeData = false;
 }
 
 /************************************************************************/
@@ -45,34 +46,41 @@ JpgLoader::JpgLoader()
     jpegDecompressor = tjInitDecompress();
 }
 
+
 JpgLoader::~JpgLoader()
 {
-    if (data) tjFree(data);
+    if (freeData) free(data);
     tjDestroy(jpegDecompressor);
+
+    //This image is shared with raster engine.
     tjFree(image);
-    image = NULL;
 }
 
+
 bool JpgLoader::open(const string& path)
 {
     clear();
 
-    bool success = false;
-    FILE *jpegFile = NULL;
-    if ((jpegFile = fopen(path.c_str(), "rb")) == NULL) return false;
+    auto jpegFile = fopen(path.c_str(), "rb");
+    if (!jpegFile) return false;
+
+    auto ret = false;
 
     //determine size
     if (fseek(jpegFile, 0, SEEK_END) < 0) goto finalize;
     if (((size = ftell(jpegFile)) < 1)) goto finalize;
     if (fseek(jpegFile, 0, SEEK_SET)) goto finalize;
 
-    data = (unsigned char *) tjAlloc(size);
+    data = (unsigned char *) malloc(size);
     if (!data) goto finalize;
 
     if (fread(data, size, 1, jpegFile) < 1) goto failure;
 
-    pointer = data;
-    success = true;
+    //FIXME: Decompress header here
+
+    ret = true;
+    freeData = true;
+
     goto finalize;
 
 failure:
@@ -80,9 +88,10 @@ failure:
 
 finalize:
     fclose(jpegFile);
-    return success;
+    return ret;
 }
 
+
 bool JpgLoader::open(const char* data, uint32_t size, bool copy)
 {
     clear();
@@ -91,24 +100,26 @@ bool JpgLoader::open(const char* data, uint32_t size, bool copy)
         this->data = (unsigned char *) malloc(size);
         if (!this->data) return false;
         memcpy((unsigned char *)this->data, data, size);
-        this->pointer = this->data;
+        freeData = true;
     } else {
-        this->pointer = (unsigned char *)data;
+        this->data = (unsigned char *) data;
     }
 
     this->size = size;
+
+    //FIXME: Decompress header here
+
     return true;
 }
 
+
 bool JpgLoader::read()
 {
-    int width, height;
-
     //decompress header
+    int width, height;
     int inSubsamp, inColorspace;
     if (tjDecompressHeader3(jpegDecompressor, data, size, &width, &height, &inSubsamp, &inColorspace) < 0) return false;
 
-    //alloc image buffer
     if (image) tjFree(image);
     image = (unsigned char *)tjAlloc(width * height * tjPixelSize[TJPF_BGRX]);
     if (!image) return false;
@@ -116,21 +127,24 @@ bool JpgLoader::read()
     //decompress jpg image
     if (tjDecompress2(jpegDecompressor, data, size, image, width, 0, height, TJPF_BGRX, 0) < 0) {
         tjFree(image);
-        image = NULL;
+        image = nullptr;
         return false;
     }
 
     vw = w = width;
     vh = h = height;
+
     return true;
 }
 
+
 bool JpgLoader::close()
 {
     clear();
     return true;
 }
 
+
 const uint32_t* JpgLoader::pixels()
 {
     return (const uint32_t*) image;

src/loaders/jpg/tvgJpgLoader.h

@@ -22,8 +22,9 @@
 #ifndef _TVG_JPG_LOADER_H_
 #define _TVG_JPG_LOADER_H_
 
-#include <turbojpeg.h>
+using tjhandle = void*;
 
+//TODO: Use Task?
 class JpgLoader : public Loader
 {
 public:
@@ -43,9 +44,9 @@ private:
 
     tjhandle jpegDecompressor;
     unsigned char* data = nullptr;
-    const unsigned char* pointer = nullptr;
-    unsigned long size = 0;
     unsigned char *image = nullptr;
+    unsigned long size = 0;
+    bool freeData = false;
 };
 
 #endif //_TVG_JPG_LOADER_H_