From c35b5b2a9ec49bd709d63df7caee398ac33da238 Mon Sep 17 00:00:00 2001
From: Vladimir Agafonkin <agafonkin@gmail.com>
Date: Tue, 7 Aug 2018 14:53:13 +0200
Subject: [PATCH] avoid expensive resizing in image/glyph atlases

---
 src/render/glyph_atlas.js | 54 ++++++++++++++++++---------------------
 src/render/image_atlas.js | 44 ++++++++++++-------------------
 2 files changed, 42 insertions(+), 56 deletions(-)

diff --git a/src/render/glyph_atlas.js b/src/render/glyph_atlas.js
index d4bdecc6315..06df12acf04 100644
--- a/src/render/glyph_atlas.js
+++ b/src/render/glyph_atlas.js
@@ -26,10 +26,9 @@ export default class GlyphAtlas {
     positions: { [string]: { [number]: GlyphPosition } };
 
     constructor(stacks: { [string]: { [number]: ?StyleGlyph } }) {
-        const image = new AlphaImage({width: 0, height: 0});
         const positions = {};
-
         const pack = new ShelfPack(0, 0, {autoResize: true});
+        const bins = [];
 
         for (const stack in stacks) {
             const glyphs = stacks[stack];
@@ -37,36 +36,33 @@ export default class GlyphAtlas {
 
             for (const id in glyphs) {
                 const src = glyphs[+id];
-                if (src && src.bitmap.width !== 0 && src.bitmap.height !== 0) {
-                    const bin = pack.packOne(
-                        src.bitmap.width + 2 * padding,
-                        src.bitmap.height + 2 * padding);
-
-                    image.resize({
-                        width: pack.w,
-                        height: pack.h
-                    });
-
-                    AlphaImage.copy(
-                        src.bitmap,
-                        image,
-                        {x: 0, y: 0},
-                        {
-                            x: bin.x + padding,
-                            y: bin.y + padding
-                        },
-                        src.bitmap);
-
-                    stackPositions[id] = {rect: bin, metrics: src.metrics};
-                }
+                if (!src || src.bitmap.width === 0 || src.bitmap.height === 0) continue;
+
+                const bin = {
+                    x: 0,
+                    y: 0,
+                    w: src.bitmap.width + 2 * padding,
+                    h: src.bitmap.height + 2 * padding
+                };
+                bins.push(bin);
+                stackPositions[id] = {rect: bin, metrics: src.metrics};
             }
         }
 
-        pack.shrink();
-        image.resize({
-            width: pack.w,
-            height: pack.h
-        });
+        pack.pack(bins, {inPlace: true});
+
+        const image = new AlphaImage({width: pack.w, height: pack.h});
+
+        for (const stack in stacks) {
+            const glyphs = stacks[stack];
+
+            for (const id in glyphs) {
+                const src = glyphs[+id];
+                if (!src || src.bitmap.width === 0 || src.bitmap.height === 0) continue;
+                const bin = positions[stack][id].rect;
+                AlphaImage.copy(src.bitmap, image, {x: 0, y: 0}, {x: bin.x + padding, y: bin.y + padding}, src.bitmap);
+            }
+        }
 
         this.image = image;
         this.positions = positions;
diff --git a/src/render/image_atlas.js b/src/render/image_atlas.js
index fb87efed1c1..647a4b5dcbb 100644
--- a/src/render/image_atlas.js
+++ b/src/render/image_atlas.js
@@ -52,41 +52,31 @@ export default class ImageAtlas {
     positions: {[string]: ImagePosition};
 
     constructor(images: {[string]: StyleImage}) {
-        const image = new RGBAImage({width: 0, height: 0});
         const positions = {};
-
         const pack = new ShelfPack(0, 0, {autoResize: true});
+        const bins = [];
 
         for (const id in images) {
             const src = images[id];
-
-            const bin = pack.packOne(
-                src.data.width + 2 * padding,
-                src.data.height + 2 * padding);
-
-            image.resize({
-                width: pack.w,
-                height: pack.h
-            });
-
-            RGBAImage.copy(
-                src.data,
-                image,
-                { x: 0, y: 0 },
-                {
-                    x: bin.x + padding,
-                    y: bin.y + padding
-                },
-                src.data);
-
+            const bin = {
+                x: 0,
+                y: 0,
+                w: src.data.width + 2 * padding,
+                h: src.data.height + 2 * padding,
+            };
+            bins.push(bin);
             positions[id] = new ImagePosition(bin, src);
         }
 
-        pack.shrink();
-        image.resize({
-            width: pack.w,
-            height: pack.h
-        });
+        pack.pack(bins, {inPlace: true});
+
+        const image = new RGBAImage({width: pack.w, height: pack.h});
+
+        for (const id in images) {
+            const src = images[id];
+            const bin = positions[id].paddedRect;
+            RGBAImage.copy(src.data, image, {x: 0, y: 0}, {x: bin.x + padding, y: bin.y + padding}, src.data);
+        }
 
         this.image = image;
         this.positions = positions;