[ui] custom canvas-based image fragment rendering (allow resizing)

webui/src/components/display/blobs/FragmentViewer.svelte

@@ -39,6 +39,7 @@
     width: 100%;
     display: flex;
     justify-content: center;
+    min-height: 0;
   }
 
   img {

webui/src/components/display/blobs/ImageViewer.svelte

@@ -204,10 +204,10 @@
       min-height: 0;
       max-height: 100%;
     }
-  }
 
-  .preview-image {
+    .preview-image {
-    margin: auto;
+      margin: auto;
+    }
   }
 
   .r6o-editor {

webui/src/util/fragments/xywh.ts

@@ -43,24 +43,20 @@ export function xywh(mediaItem: HTMLImageElement | HTMLVideoElement) {
 }
 
 /**
- * Applies the media fragment when the image has loaded. We need the image's
+ * Applies the media fragment when the image has loaded.
- * original width and height.
  */
 function addImageLoadListener(mediaFragment: MediaFragment) {
-  // Base64-encoded transparent 1x1 pixel GIF
-  const TRANSPARENT_GIF =
-    "data:image/gif;base64,R0lGODlhAQABAPAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==";
   const mediaItem = mediaFragment.mediaItem;
-  const onload = function () {
+  // Prevent onload firing when the fragment loads; but still react when `src`
-    // Prevent onload firing when the 1x1 pixel GIF loads; but still react when `src`
+  // is changed programatically.
-    // is changed programatically.
+  let lastSrc: string;
-    if (mediaItem.src !== TRANSPARENT_GIF) {
+  function onload() {
+    if (mediaItem.src !== lastSrc) {
       // Required on reloads because of size calculations.
-      mediaItem.style.cssText = "";
       applyFragment(mediaFragment);
-      mediaItem.src = TRANSPARENT_GIF;
+      lastSrc = mediaItem.src;
     }
-  };
+  }
   mediaItem.addEventListener("load", onload);
 }
 
@@ -86,34 +82,26 @@ function addVideoLoadListener(mediaFragment: MediaFragment) {
  * 2D transformation according to the fragment's x and y values.
  */
 function applyFragment(fragment: MediaFragment) {
-  let x: string, y: string, w: string, h: string;
-  const originalWidth =
-    fragment.mediaType === "img"
-      ? fragment.mediaItem.width
-      : fragment.mediaItem.videoWidth;
-  const originalHeight =
-    fragment.mediaType === "img"
-      ? fragment.mediaItem.height
-      : fragment.mediaItem.videoHeight;
-  // Unit is pixel:
-  if (fragment.unit === "pixel:") {
-    const scale =
-      fragment.mediaType === "img"
-        ? originalWidth / fragment.mediaItem.naturalWidth
-        : originalWidth / fragment.mediaItem.clientWidth;
-    w = fragment.w * scale + "px";
-    h = fragment.h * scale + "px";
-    x = "-" + fragment.x * scale + "px";
-    y = "-" + fragment.y * scale + "px";
-    // Unit is percent:
-  } else {
-    w = (originalWidth * fragment.w) / 100 + "px";
-    h = (originalHeight * fragment.h) / 100 + "px";
-    x = "-" + (originalWidth * fragment.x) / 100 + "px";
-    y = "-" + (originalHeight * fragment.y) / 100 + "px";
-  }
   // Media item is a video
   if (fragment.mediaType === "video") {
+    let x: string, y: string, w: string, h: string;
+    const originalWidth = fragment.mediaItem.videoWidth;
+    const originalHeight = fragment.mediaItem.videoHeight;
+    // Unit is pixel:
+    if (fragment.unit === "pixel:") {
+      const scale = originalWidth / fragment.mediaItem.clientWidth;
+      w = fragment.w * scale + "px";
+      h = fragment.h * scale + "px";
+      x = "-" + fragment.x * scale + "px";
+      y = "-" + fragment.y * scale + "px";
+      // Unit is percent:
+    } else {
+      w = (originalWidth * fragment.w) / 100 + "px";
+      h = (originalHeight * fragment.h) / 100 + "px";
+      x = "-" + (originalWidth * fragment.x) / 100 + "px";
+      y = "-" + (originalHeight * fragment.y) / 100 + "px";
+    }
+
     const wrapper = document.createElement("div");
     wrapper.style.cssText +=
       "overflow:hidden;" +
@@ -148,25 +136,23 @@ function applyFragment(fragment: MediaFragment) {
     }
     // Media item is an image
   } else {
-    fragment.mediaItem.style.cssText +=
+    let x: number, y: number, w: number, h: number;
-      "width:" +
+    if (fragment.unit === "pixel:") {
-      w +
+      x = fragment.x;
-      ";" +
+      y = fragment.y;
-      "height:" +
+      w = fragment.w;
-      h +
+      h = fragment.h;
-      ";" +
+    } else {
-      "background:url(" +
+      x = (fragment.x / 100) * fragment.mediaItem.naturalWidth;
-      fragment.mediaItem.src +
+      y = (fragment.y / 100) * fragment.mediaItem.naturalHeight;
-      ") " + // background-image
+      w = (fragment.w / 100) * fragment.mediaItem.naturalWidth;
-      "no-repeat " + // background-repeat
+      h = (fragment.h / 100) * fragment.mediaItem.naturalHeight;
-      x +
+    }
-      " " +
+    const canvas = document.createElement("canvas");
-      y +
+    canvas.width = w;
-      "; " + // background-position
+    canvas.height = h;
-      "background-size: " +
+    const context = canvas.getContext("2d");
-      originalWidth +
+    context.drawImage(fragment.mediaItem, x, y, w, h, 0, 0, w, h);
-      "px " +
+    fragment.mediaItem.src = canvas.toDataURL();
-      originalHeight +
-      "px;";
   }
 }