docs, notes and cleanup...

Signed-off-by: Alex A. Naanou <alex.nanou@gmail.com>

Viewer/doc/HACKS

@@ -3,6 +3,20 @@ Hacks and fixes
 ===============
 
 
+20201104:
+Chrome v83 / Electron 9.3.3
+
+WebKit canvas' .drawImage(..) ignores its and images .style.imageOrientation 
+unless both are added to DOM.
+
+FIX:
+- features/app.js: img2canvas(..) quietly adds the elements to DOM and then cleans up
+
+TODO:
+- test in browser...
+- test in newer versions of browser / electron...
+- if not fixed report...
+
 
 
 20200830: 
@@ -24,7 +38,7 @@ FIX:
 - index.html / electron.html: added <video> tag with data/blank.mp4 as source
 
 TODO:
-- document and post a bug report
+- report this...
 
 
 

Viewer/features/app.js

@@ -32,17 +32,16 @@ var widgets = require('features/ui-widgets')
 /*********************************************************************/
 // helpers...
 
+// XXX this includes a WebKit bug patch -- see inside...
 var img2canvas = 
 function({url, orientation, flipped}, callback){
-	var img = new Image
-
 
 	// XXX PATCH...
 	// XXX <canvas>.drawImage(..) seems to take EXIF into account, ignoring 
 	// 		the .imageOrientation setting both the canvas and image are in
 	// 		DOM and the image needs to be added to dom before .src is set
 	var PATCHED_ELEMENTS
-	var PATCH_BUG = function(e){
+	var PATCH = function(e){
 		PATCHED_ELEMENTS = 
 			PATCHED_ELEMENTS
 			|| document.body.appendChild(
@@ -56,13 +55,13 @@ function({url, orientation, flipped}, callback){
 						this.style.opacity = 0
 						this.style.overflow = 'hidden' }))
 		PATCHED_ELEMENTS.appendChild(e) }
+	// XXX PATCH...
 	var CLEANUP_PATCH = function(){
 		PATCHED_ELEMENTS
 			.parentElement
 				.removeChild(PATCHED_ELEMENTS) }
-	// XXX END PATCH...
-	
 
+	var img = new Image
 	img.onload = function(){
 		var width = this.naturalWidth
 		var height = this.naturalHeight
@@ -71,7 +70,7 @@ function({url, orientation, flipped}, callback){
 		c.style.imageOrientation = 'none'
 
 		// XXX PATCH...
-		PATCH_BUG(c)
+		PATCH(c)
 
 		var ctx = c.getContext('2d')
 		// prepare for rotate...
@@ -104,15 +103,16 @@ function({url, orientation, flipped}, callback){
 	// prevent the browser from rotating the image via exif...
 	img.style.imageOrientation = 'none'
 	img.crossOrigin = ''
-	img.src = url 
 
 	// XXX PATCH...
-	PATCH_BUG(img)
+	PATCH(img)
 
+	img.src = url 
 	return img }
 
 
 
+
 /*********************************************************************/
 
 var Widget = 

Viewer/features/sharp.js

@@ -649,11 +649,10 @@ module.Sharp = core.ImageGridFeatures.Feature({
 	isApplicable: function(){ return !!sharp },
 
 	handlers: [
-		/* XXX not sure if we need this...
-		// XXX this is best done in a thread + needs to be abortable...
+		/* XXX this needs to be run in the background...
+		// XXX this is best done in a thread + needs to be abortable (on .load(..))...
 		['loadImages',
 			function(){
-				//this.cacheImageMetadata('all', false) }],
 				this.cacheImageMetadata('all') }],
 		//*/