import

DSTexCompress/FreeImage/Examples/Generic/CreateAlpha.cpp

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+// ==========================================================
+// Alpha channel manipulation example
+//
+// Design and implementation by 
+// - Herv<72> Drolon
+//
+// This file is part of FreeImage 3
+//
+// COVERED CODE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTY
+// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES
+// THAT THE COVERED CODE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE
+// OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE COVERED
+// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT
+// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY
+// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL
+// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER
+// THIS DISCLAIMER.
+//
+// Use at own risk!
+// ==========================================================
+
+//   This example shows how to create a transparent image from any input image
+//   using the greyscale version of the input image as the alpha channel mask.
+//   The alpha channel is set using the FreeImage_SetChannel function.
+// 
+//
+// ==========================================================
+
+#include <stdio.h>
+#include "FreeImage.h"
+
+// ----------------------------------------------------------
+
+/** Generic image loader
+	@param lpszPathName Pointer to the full file name
+	@param flag Optional load flag constant
+	@return Returns the loaded dib if successful, returns NULL otherwise
+*/
+FIBITMAP* GenericLoader(const char* lpszPathName, int flag) {
+	FREE_IMAGE_FORMAT fif = FIF_UNKNOWN;
+
+	// check the file signature and deduce its format
+	// (the second argument is currently not used by FreeImage)
+	fif = FreeImage_GetFileType(lpszPathName, 0);
+	if(fif == FIF_UNKNOWN) {
+		// no signature ?
+		// try to guess the file format from the file extension
+		fif = FreeImage_GetFIFFromFilename(lpszPathName);
+	}
+	// check that the plugin has reading capabilities ...
+	if((fif != FIF_UNKNOWN) && FreeImage_FIFSupportsReading(fif)) {
+		// ok, let's load the file
+		FIBITMAP *dib = FreeImage_Load(fif, lpszPathName, flag);
+		// unless a bad file format, we are done !
+		return dib;
+	}
+	return NULL;
+}
+
+/** Generic image writer
+	@param dib Pointer to the dib to be saved
+	@param lpszPathName Pointer to the full file name
+	@param flag Optional save flag constant
+	@return Returns true if successful, returns false otherwise
+*/
+bool GenericWriter(FIBITMAP* dib, const char* lpszPathName, int flag) {
+	FREE_IMAGE_FORMAT fif = FIF_UNKNOWN;
+	BOOL bSuccess = FALSE;
+
+	if(dib) {
+		// try to guess the file format from the file extension
+		fif = FreeImage_GetFIFFromFilename(lpszPathName);
+		if(fif != FIF_UNKNOWN ) {
+			// check that the plugin has sufficient writing and export capabilities ...
+			WORD bpp = FreeImage_GetBPP(dib);
+			if(FreeImage_FIFSupportsWriting(fif) && FreeImage_FIFSupportsExportBPP(fif, bpp)) {
+				// ok, we can save the file
+				bSuccess = FreeImage_Save(fif, dib, lpszPathName, flag);
+				// unless an abnormal bug, we are done !
+			}
+		}
+	}
+	return (bSuccess == TRUE) ? true : false;
+}
+
+// ----------------------------------------------------------
+
+/**
+	FreeImage error handler
+	@param fif Format / Plugin responsible for the error 
+	@param message Error message
+*/
+void FreeImageErrorHandler(FREE_IMAGE_FORMAT fif, const char *message) {
+	printf("\n*** "); 
+	if(fif != FIF_UNKNOWN) {
+		printf("%s Format\n", FreeImage_GetFormatFromFIF(fif));
+	}
+	printf(message);
+	printf(" ***\n");
+}
+
+// ----------------------------------------------------------
+
+
+/**
+ Creates a 32-bit transparent image using the black channel of the source image
+ @param src Source image
+ @return Returns a 32-bit transparent image
+*/
+FIBITMAP* CreateAlphaFromLightness(FIBITMAP *src) {
+	// create a 32-bit image from the source
+	FIBITMAP *dst = FreeImage_ConvertTo32Bits(src);
+
+	// create a 8-bit mask
+	FreeImage_Invert(src);
+	FIBITMAP *mask = FreeImage_ConvertTo8Bits(src);
+	FreeImage_Invert(src);
+
+	// insert the mask as an alpha channel
+	FreeImage_SetChannel(dst, mask, FICC_ALPHA);
+
+	// free the mask and return
+	FreeImage_Unload(mask);
+
+	return dst;
+}
+
+int 
+main(int argc, char *argv[]) {
+	
+	// call this ONLY when linking with FreeImage as a static library
+#ifdef FREEIMAGE_LIB
+	FreeImage_Initialise();
+#endif // FREEIMAGE_LIB
+
+	// initialize your own FreeImage error handler
+
+	FreeImage_SetOutputMessage(FreeImageErrorHandler);
+
+	// print version & copyright infos
+
+	printf("FreeImage version : %s", FreeImage_GetVersion());
+	printf("\n");
+	printf(FreeImage_GetCopyrightMessage());
+	printf("\n");
+
+
+	if(argc != 3) {
+		printf("Usage : CreateAlpha <input file name> <output file name>\n");
+		return 0;
+	}
+
+	// Load the source image
+	FIBITMAP *src = GenericLoader(argv[1], 0);
+	if(src) {
+		// Create a transparent image from the lightness image of src
+		FIBITMAP *dst = CreateAlphaFromLightness(src);
+
+		if(dst) {
+			// Save the destination image
+			bool bSuccess = GenericWriter(dst, argv[2], 0);
+			if(!bSuccess) {
+				printf("\nUnable to save %s file", argv[2]);
+				printf("\nThis format does not support 32-bit images");
+			}
+
+			// Free dst
+			FreeImage_Unload(dst);
+		}
+
+		// Free src
+		FreeImage_Unload(src);
+	}
+
+	// call this ONLY when linking with FreeImage as a static library
+#ifdef FREEIMAGE_LIB
+	FreeImage_DeInitialise();
+#endif // FREEIMAGE_LIB
+
+	return 0;
+}