Scale screenshots of HiDPI devices to logical screen size

diff --git a/wcfsetup/install/files/js/WCF.Attachment.js b/wcfsetup/install/files/js/WCF.Attachment.js
index bb7c33130a0634d3871611da371cc8f12652eded..8abb95b879f5e1602cafbc466c50227b3a079b3b 100644 (file)
--- a/wcfsetup/install/files/js/WCF.Attachment.js
+++ b/wcfsetup/install/files/js/WCF.Attachment.js
@@ -320,9 +320,6 @@ if (COMPILER_TARGET_DEFAULT) {
                                        var maxSize = this._buttonSelector.data('maxSize');
                                        
                                        var resizer = new ImageResizer();
-                                       var maxWidth = this._options.autoScale.maxWidth;
-                                       var maxHeight = this._options.autoScale.maxHeight;
-                                       var quality = this._options.autoScale.quality;
                                        
                                        // Resize the images in series.
                                        // As our resizer is based on Pica it will use multiple workers per image if possible.
@@ -339,6 +336,20 @@ if (COMPILER_TARGET_DEFAULT) {
                                                        var promise = resizer.loadFile(file)
                                                                .then((function (result) {
                                                                        var exif = result.exif;
+                                                                       var maxWidth = this._options.autoScale.maxWidth;
+                                                                       var maxHeight = this._options.autoScale.maxHeight;
+                                                                       var quality = this._options.autoScale.quality;
+                                                                       
+                                                                       if (window.devicePixelRatio >= 2) {
+                                                                               var realWidth = window.screen.width * window.devicePixelRatio;
+                                                                               var realHeight = window.screen.height * window.devicePixelRatio;
+                                                                               // Check whether the width of the image is roughly the width of the physical screen, and
+                                                                               // the height of the image is at least the height of the physical screen.
+                                                                               if (realWidth - 10 < result.image.width && result.image.width < realWidth + 10 && realHeight - 10 < result.image.height) {
+                                                                                       // This appears to be a screenshot from a HiDPI device in portrait mode: Scale to logical size
+                                                                                       maxWidth = Math.min(maxWidth, window.screen.width);
+                                                                               }
+                                                                       }
                                                                        
                                                                        return resizer.resize(result.image, maxWidth, maxHeight, quality, file.size > maxSize, timeout)
                                                                                .then((function (resizedImage) {