From 3cff8e7d101a528e392d885420de118cccca6ae5 Mon Sep 17 00:00:00 2001
From: Stanley Yip <stanley_yip@brown.edu>
Date: Tue, 22 Oct 2019 16:39:52 -0400
Subject: touch + inking can now pan with two fingers

---
 src/client/views/InkingCanvas.tsx                  | 35 +++++++++++++++++-----
 src/client/views/Touchable.tsx                     | 20 ++++++++++---
 .../collectionFreeForm/CollectionFreeFormView.tsx  | 15 ++++++++--
 3 files changed, 57 insertions(+), 13 deletions(-)

(limited to 'src')

diff --git a/src/client/views/InkingCanvas.tsx b/src/client/views/InkingCanvas.tsx
index 7651060af..2f3083cfe 100644
--- a/src/client/views/InkingCanvas.tsx
+++ b/src/client/views/InkingCanvas.tsx
@@ -10,6 +10,8 @@ import { UndoManager } from "../util/UndoManager";
 import { StrokeData, InkField, InkTool } from "../../new_fields/InkField";
 import { Doc } from "../../new_fields/Doc";
 import { Cast, PromiseValue, NumCast } from "../../new_fields/Types";
+import { Touchable } from "./Touchable";
+import { InteractionUtils } from "../util/InteractionUtils";
 
 interface InkCanvasProps {
     getScreenTransform: () => Transform;
@@ -20,7 +22,7 @@ interface InkCanvasProps {
 }
 
 @observer
-export class InkingCanvas extends React.Component<InkCanvasProps> {
+export class InkingCanvas extends Touchable<InkCanvasProps> {
     maxCanvasDim = 8192 / 2; // 1/2 of the maximum canvas dimension for Chrome
     @observable inkMidX: number = 0;
     @observable inkMidY: number = 0;
@@ -93,6 +95,18 @@ export class InkingCanvas extends React.Component<InkCanvasProps> {
         }
     }
 
+    @action
+    handle1PointerMove = (e: TouchEvent) => {
+        e.stopPropagation();
+        e.preventDefault();
+        let pointer = e.targetTouches.item(0);
+        if (pointer) {
+            this.handleMove(pointer.clientX, pointer.clientY);
+        }
+    }
+
+    handle2PointersMove = () => { }
+
     @action
     onPointerUp = (e: PointerEvent): void => {
         document.removeEventListener("pointermove", this.onPointerMove, true);
@@ -116,21 +130,28 @@ export class InkingCanvas extends React.Component<InkCanvasProps> {
         batch.end();
     }
 
-    @action
-    onPointerMove = (e: PointerEvent): void => {
-        e.stopPropagation();
-        e.preventDefault();
+    handleMove = (x: number, y: number) => {
         if (InkingControl.Instance.selectedTool !== InkTool.Eraser) {
             let data = this.inkData;  // add points to new line as it is being drawn
             let strokeData = data.get(this._currentStrokeId);
             if (strokeData) {
-                strokeData.pathData.push(this.relativeCoordinatesForEvent(e.clientX, e.clientY));
+                strokeData.pathData.push(this.relativeCoordinatesForEvent(x, y));
                 data.set(this._currentStrokeId, strokeData);
             }
             this.inkData = data;
         }
     }
 
+    @action
+    onPointerMove = (e: PointerEvent): void => {
+        if (InteractionUtils.IsType(e, InteractionUtils.TOUCH)) {
+            return;
+        }
+        e.stopPropagation();
+        e.preventDefault();
+        this.handleMove(e.clientX, e.clientY);
+    }
+
     relativeCoordinatesForEvent = (ex: number, ey: number): { x: number, y: number } => {
         let [x, y] = this.props.getScreenTransform().transformPoint(ex, ey);
         return { x, y };
@@ -183,7 +204,7 @@ export class InkingCanvas extends React.Component<InkCanvasProps> {
         let svgCanvasStyle = InkingControl.Instance.selectedTool !== InkTool.None && !this.props.Document.isBackground ? "canSelect" : "noSelect";
         return (
             <div className="inkingCanvas">
-                <div className={`inkingCanvas-${svgCanvasStyle}`} onPointerDown={this.onPointerDown} onTouchStart={(e) => e.stopPropagation()} />
+                <div className={`inkingCanvas-${svgCanvasStyle}`} onPointerDown={this.onPointerDown} onTouchStart={this.onTouchStart} />
                 {this.props.children()}
                 {this.drawnPaths}
             </div >
diff --git a/src/client/views/Touchable.tsx b/src/client/views/Touchable.tsx
index e9671ab8b..4955129ba 100644
--- a/src/client/views/Touchable.tsx
+++ b/src/client/views/Touchable.tsx
@@ -20,6 +20,15 @@ export abstract class Touchable<T> extends React.Component<T> {
             let pt = e.targetTouches.item(i);
             this.prevPoints.set(pt.identifier, pt);
         }
+
+        switch (e.targetTouches.length) {
+            case 1:
+                this.handle1PointerDown();
+                break;
+            case 2:
+                this.handle2PointersDown(e);
+        }
+
         document.removeEventListener("touchmove", this.onTouch);
         document.addEventListener("touchmove", this.onTouch);
         document.removeEventListener("touchend", this.onTouchEnd);
@@ -36,10 +45,10 @@ export abstract class Touchable<T> extends React.Component<T> {
         this._touchDrag = true;
         switch (e.targetTouches.length) {
             case 1:
-                this.handle1Pointer(e)
+                this.handle1PointerMove(e)
                 break;
             case 2:
-                this.handle2Pointers(e);
+                this.handle2PointersMove(e);
                 break;
         }
     }
@@ -70,13 +79,16 @@ export abstract class Touchable<T> extends React.Component<T> {
         document.removeEventListener("touchend", this.onTouchEnd);
     }
 
-    handle1Pointer = (e: TouchEvent): any => {
+    handle1PointerMove = (e: TouchEvent): any => {
         e.stopPropagation();
         e.preventDefault();
     }
 
-    handle2Pointers = (e: TouchEvent): any => {
+    handle2PointersMove = (e: TouchEvent): any => {
         e.stopPropagation();
         e.preventDefault();
     }
+
+    handle1PointerDown = (): any => { };
+    handle2PointersDown = (e: React.TouchEvent): any => { };
 }
\ No newline at end of file
diff --git a/src/client/views/collections/collectionFreeForm/CollectionFreeFormView.tsx b/src/client/views/collections/collectionFreeForm/CollectionFreeFormView.tsx
index 440a0a8e5..123941b03 100644
--- a/src/client/views/collections/collectionFreeForm/CollectionFreeFormView.tsx
+++ b/src/client/views/collections/collectionFreeForm/CollectionFreeFormView.tsx
@@ -356,7 +356,7 @@ export class CollectionFreeFormView extends CollectionSubView(PanZoomDocument) {
         }
     }
 
-    handle1Pointer = (e: TouchEvent) => {
+    handle1PointerMove = (e: TouchEvent) => {
         // panning a workspace
         if (!e.cancelBubble && this.props.active()) {
             let pt = e.targetTouches.item(0);
@@ -368,7 +368,7 @@ export class CollectionFreeFormView extends CollectionSubView(PanZoomDocument) {
         }
     }
 
-    handle2Pointers = (e: TouchEvent) => {
+    handle2PointersMove = (e: TouchEvent) => {
         // pinch zooming
         if (!e.cancelBubble) {
             let pt1: Touch | null = e.targetTouches.item(0);
@@ -413,6 +413,17 @@ export class CollectionFreeFormView extends CollectionSubView(PanZoomDocument) {
         e.preventDefault();
     }
 
+    handle2PointersDown = (e: React.TouchEvent) => {
+        let pt1: React.Touch | null = e.targetTouches.item(0);
+        let pt2: React.Touch | null = e.targetTouches.item(1);
+        if (!pt1 || !pt2) return;
+
+        let centerX = Math.min(pt1.clientX, pt2.clientX) + Math.abs(pt2.clientX - pt1.clientX) / 2;
+        let centerY = Math.min(pt1.clientY, pt2.clientY) + Math.abs(pt2.clientY - pt1.clientY) / 2;
+        this._lastX = centerX;
+        this._lastY = centerY;
+    }
+
     cleanUpInteractions = () => {
         document.removeEventListener("pointermove", this.onPointerMove);
         document.removeEventListener("pointerup", this.onPointerUp);
-- 
cgit v1.2.3-70-g09d2