import analyser and migrate to solidjs, untested

script/viewer/Panner/CenteredPanZoom.ts

@@ -0,0 +1,102 @@
+import {Viewport, Point} from './Viewport';
+
+export interface CenteredPanZoomOptions {
+	screenWidth: number;
+	screenHeight: number;
+	scale?: number;
+	contentSize: {
+		width: number;
+		height: number;
+	}
+}
+
+export class CenteredPanZoom {
+	screen: Viewport;
+	viewport: Viewport;
+	scale: number;
+	contentSize: {
+		width: number;
+		height: number;
+	};
+
+	constructor(options: CenteredPanZoomOptions) {
+		this.screen = new Viewport({
+			x: 0,
+			y: 0,
+			width: options.screenWidth,
+			height: options.screenHeight
+		});
+		this.viewport = new Viewport({
+			x: 0,
+			y: 0,
+			width: options.screenWidth,
+			height: options.screenHeight
+		});
+		this.scale = options.scale || 1;
+		this.contentSize = options.contentSize;
+	}
+
+	setSize(width, height) {
+		this.screen.width = width;
+		this.screen.height = height;
+		this.viewport.width = width * this.scale;
+		this.viewport.height = height * this.scale;
+		this.constrainPan(true);
+	}
+
+	setContentSize(width, height) {
+		this.contentSize = {width, height};
+		this.constrainPan(true);
+	}
+
+	pan(screenX, screenY) {
+		this.viewport.x = this.viewport.x + screenX;
+		this.viewport.y = this.viewport.y + screenY;
+		this.constrainPan();
+	}
+
+	constrainPan(strict = false) {
+		const minX = (strict) ? 0 : this.screen.width * 0.5;
+		const minY = (strict) ? 0 : this.screen.height * 0.5;
+		this.viewport.x = Math.min(minX, this.viewport.x);
+		this.viewport.y = Math.min(minY * 0.5, this.viewport.y);
+		const maxY = (this.screen.height - (this.contentSize.height * this.scale)) - (strict ? 0 : this.screen.height * 0.5);
+		const maxX = (this.screen.width - (this.contentSize.width * this.scale)) - (strict ? 0 : this.screen.width * 0.5);
+		this.viewport.y = Math.max(maxY, this.viewport.y);
+		this.viewport.x = Math.max(maxX, this.viewport.x);
+		if (maxY > ((strict) ? 0 : this.screen.height * 0.5)) {
+			this.viewport.y = Math.floor(maxY / 2);
+		}
+		if (maxX > ((strict) ? 0 : this.screen.width * 0.5)) {
+			this.viewport.x = Math.floor(maxX / 2);
+		}
+	}
+
+	panFrom(screenStart: Point, screenEnd: Point) {
+		this.pan(screenEnd.x - screenStart.x, screenEnd.y - screenStart.y);
+	}
+
+	//find zoom point in pre-zoom viewport
+	//make that point the same in the post-zoom viewport
+	zoom(scale: number, screenCenter: Point) {
+		const v1 = Viewport.convert(screenCenter, {
+			from: this.screen,
+			to: this.viewport
+		});
+		this.viewport.x = this.viewport.x * (scale / this.scale);
+		this.viewport.y = this.viewport.y * (scale / this.scale);
+		this.viewport.width = this.screen.width * scale;
+		this.viewport.height = this.screen.height * scale;
+		const minScale = Math.min(this.screen.width / this.contentSize.width, this.screen.height / this.contentSize.height);
+		scale = Math.max(minScale, scale);
+		this.scale = scale;
+
+		const v2 = Viewport.convert(screenCenter, {
+			from: this.screen,
+			to: this.viewport
+		});
+		const deltaX = v2.x - v1.x;
+		const deltaY = v2.y - v1.y;
+		this.pan(deltaX * scale, deltaY * scale);
+	}
+}