Explicitly handle Image AlphaMode enum instead of treating as bool

Co-authored-by: K. S. Ernest (iFire) Lee <[email protected]>

Author: aaronfranke

drivers/png/png_driver_common.cpp

@@ -152,7 +152,7 @@ Error image_to_png(const Ref<Image> &p_image, Vector<uint8_t> &p_buffer) {
 			png_img.format = PNG_FORMAT_RGBA;
 			break;
 		default:
-			if (source_image->detect_alpha()) {
+			if (source_image->detect_alpha() != Image::ALPHA_NONE) {
 				source_image->convert(Image::FORMAT_RGBA8);
 				png_img.format = PNG_FORMAT_RGBA;
 			} else {

editor/import/resource_importer_layered_texture.cpp

@@ -349,7 +349,7 @@ Error ResourceImporterLayeredTexture::import(ResourceUID::ID p_source_id, const
 		//if using video ram, optimize
 		if (channel_pack == 0) {
 			//remove alpha if not needed, so compression is more efficient
-			if (image->get_format() == Image::FORMAT_RGBA8 && !image->detect_alpha()) {
+			if (image->get_format() == Image::FORMAT_RGBA8 && image->detect_alpha() == Image::ALPHA_NONE) {
 				image->convert(Image::FORMAT_RGB8);
 			}
 		} else if (image->get_format() < Image::FORMAT_RGBA8) {

modules/webp/webp_common.cpp

@@ -60,7 +60,7 @@ Vector<uint8_t> _webp_packer(const Ref<Image> &p_image, float p_quality, bool p_
 		Error error = img->decompress();
 		ERR_FAIL_COND_V_MSG(error != OK, Vector<uint8_t>(), "Couldn't decompress image.");
 	}
-	if (img->detect_alpha()) {
+	if (img->detect_alpha() != Image::ALPHA_NONE) {
 		img->convert(Image::FORMAT_RGBA8);
 	} else {
 		img->convert(Image::FORMAT_RGB8);