Merge pull request #57 from nativescript-community/feat-ios-set-matrix

feat(ui-canvas): Added support for iOS Canvas setMatrix

Author: farfromrefug

src/ui-canvas/canvas.d.ts

@@ -191,7 +191,7 @@ export class Canvas extends ProxyClass {
     clipPath(path: Path, op: Op): boolean;
     setBitmap(image);
     // getSaveCount(): number;
-    // setMatrix(param0: android.graphics.Matrix): void;
+    setMatrix(matrix: Matrix): void;
     // getClipBounds(param0: android.graphics.Rect): boolean;
     // saveLayerAlpha(param0: number, param1: number, param2: number, param3: number, param4: number): number;
     // restoreToCount(param0: number): void;

src/ui-canvas/canvas.ios.ts

@@ -1,5 +1,5 @@
 /* eslint-disable no-redeclare */
-import { Color, Font, ImageSource, View } from '@nativescript/core';
+import { Color, Font, ImageSource, Screen, View } from '@nativescript/core';
 import { FontStyleType, FontWeightType } from '@nativescript/core/ui/styling/font';
 import {
     Canvas as ICanvas,
@@ -1450,9 +1450,17 @@ export class Canvas implements ICanvas {
         console.error('Method not implemented:', 'skew');
     }
 
-    // setMatrix(matrix: Matrix) {
-    //     CGContextConcatCTM(this.ctx, matrix.mTransform);
-    // }
+    setMatrix(matrix: Matrix): void {
+        // TODO: Find a better way to implement matrix set
+        const density = Screen.mainScreen.scale;
+        const currentMatrix = this.getMatrix();
+        const invertedTransform = CGAffineTransformInvert(currentMatrix.mTransform);
+        const scaleTransform = CGAffineTransformMake(density, 0, 0, -density, 0, density * this.getHeight());
+
+        CGContextConcatCTM(this.ctx, invertedTransform);
+        CGContextConcatCTM(this.ctx, scaleTransform);
+        CGContextConcatCTM(this.ctx, matrix.mTransform);
+    }
     getMatrix(): Matrix {
         return new Matrix(CGContextGetCTM(this.ctx));
     }