From 17f13885c7dafcc5af1e884fcdf8e313a35db1d5 Mon Sep 17 00:00:00 2001
From: Aiosa <469130@mail.muni.cz>
Date: Tue, 26 Nov 2024 00:48:43 +0100
Subject: [PATCH] Add back overlapFraction logic for webgl drawer.

---
 src/webgldrawer.js | 34 ++++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 12 deletions(-)

diff --git a/src/webgldrawer.js b/src/webgldrawer.js
index 57094e37..a7e596da 100644
--- a/src/webgldrawer.js
+++ b/src/webgldrawer.js
@@ -872,10 +872,18 @@
         }
 
         _setupTextureHandlers() {
-            const _this = this;
             const tex2DCompatibleLoader = (tile, data) => {
                 let tiledImage = tile.tiledImage;
-                let gl = _this._gl;
+                let gl = this._gl;
+
+                let sourceWidthFraction, sourceHeightFraction;
+                if (tile.sourceBounds) {
+                    sourceWidthFraction = Math.min(tile.sourceBounds.width, data.width) / data.width;
+                    sourceHeightFraction = Math.min(tile.sourceBounds.height, data.height) / data.height;
+                } else {
+                    sourceWidthFraction = 1;
+                    sourceHeightFraction = 1;
+                }
 
                 // create a gl Texture for this tile and bind the canvas with the image data
                 let texture = gl.createTexture();
@@ -884,16 +892,18 @@
                 if( overlap > 0){
                     // calculate the normalized position of the rect to actually draw
                     // discarding overlap.
-                    let overlapFraction = _this._calculateOverlapFraction(tile, tiledImage);
+                    let overlapFraction = this._calculateOverlapFraction(tile, tiledImage);
 
-                    let left = tile.x === 0 ? 0 : overlapFraction.x;
-                    let top = tile.y === 0 ? 0 : overlapFraction.y;
-                    let right = tile.isRightMost ? 1 : 1 - overlapFraction.x;
-                    let bottom = tile.isBottomMost ? 1 : 1 - overlapFraction.y;
-                    position = _this._makeQuadVertexBuffer(left, right, top, bottom);
+                    let left = (tile.x === 0 ? 0 : overlapFraction.x) * sourceWidthFraction;
+                    let top = (tile.y === 0 ? 0 : overlapFraction.y) * sourceHeightFraction;
+                    let right = (tile.isRightMost ? 1 : 1 - overlapFraction.x) * sourceWidthFraction;
+                    let bottom = (tile.isBottomMost ? 1 : 1 - overlapFraction.y) * sourceHeightFraction;
+                    position = this._makeQuadVertexBuffer(left, right, top, bottom);
+                } else if (sourceWidthFraction === 1 && sourceHeightFraction === 1) {
+                    // no overlap and no padding: this texture can use the unit quad as its position data
+                    position = this._unitQuad;
                 } else {
-                    // no overlap: this texture can use the unit quad as its position data
-                    position = _this._unitQuad;
+                    position = this._makeQuadVertexBuffer(0, sourceWidthFraction, 0, sourceHeightFraction);
                 }
 
                 gl.activeTexture(gl.TEXTURE0);
@@ -901,8 +911,8 @@
                 // Set the parameters so we can render any size image.
                 gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
                 gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
-                gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, _this._textureFilter());
-                gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, _this._textureFilter());
+                gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, this._textureFilter());
+                gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, this._textureFilter());
 
                 try{
                     // This depends on gl.TEXTURE_2D being bound to the texture