Figuring out theright geometry for scaling and translating...

map/src/components/double-touch-handler.tsx

@@ -6,6 +6,7 @@ import { Point } from './viewport';
 
 interface DoubleTouchHandlerProps {
   updateZoom: (zoomFactor: number, center: Point) => void;
+  updateShift: (shiftDelta: Point) => void;
   children: any;
 }
 
@@ -88,10 +89,19 @@ const DoubleTouchHandler: react.FC<DoubleTouchHandlerProps> = (
           distance: touchState.distance,
           initialZoom: 1,
         });
-        props.updateZoom(factor, {
+        const previousCenter = {
+          x: (touchState.touches[0].x + touchState.touches[1].x) / 2,
+          y: (touchState.touches[0].y + touchState.touches[1].y) / 2,
+        };
+        const currentCenter = {
           x: (event.touches[0].pageX + event.touches[1].pageX) / 2,
           y: (event.touches[0].pageY + event.touches[1].pageY) / 2,
-        });
+        };
+        props.updateZoom(factor, currentCenter);
+        // props.updateShift({
+        //   x: currentCenter.x - previousCenter.x,
+        //   y: currentCenter.y - previousCenter.y,
+        // });
       }
     }
   };
@@ -103,7 +113,7 @@ const DoubleTouchHandler: react.FC<DoubleTouchHandlerProps> = (
 
   return (
     <div
-      className='viewport single-touch-handler'
+      className='viewport double-touch-handler'
       onTouchStart={touchStartHandler}
       onTouchMove={throtteledTouchMoveHandler}
       onTouchEnd={touchEndHandler}

map/src/components/layer.tsx

@@ -18,7 +18,7 @@ const Layer: react.FC<{
     <div
       className='background'
       style={{
-        transform: `translate(${-props.shift.x}px, ${-props.shift.y}px) scale(${
+        transform: `translate(${props.shift.x}px, ${props.shift.y}px) scale(${
           props.zoom
         })`,
       }}

map/src/components/mouse-handler.tsx

@@ -6,13 +6,13 @@ import { Point } from './viewport';
 
 interface MouseHandlerProps {
   updateShift: (shiftDelta: Point) => void;
+  updateZoom: (zoomFactor: number, center: Point) => void;
   children: any;
 }
 
 const MouseHandler: react.FC<MouseHandlerProps> = (
   props: MouseHandlerProps
 ) => {
-
   const initialMouseState = {
     down: false,
     starting: { x: -1, y: -1 },
@@ -24,7 +24,7 @@ const MouseHandler: react.FC<MouseHandlerProps> = (
 
   const genericHandler = (event: any) => {
     console.log('Log - Event: ' + event.type);
-    if (event.type.startsWith('mouse')) {
+    if (event.pageX !== undefined) {
       console.log(`Mouse : ${event.pageX}, ${event.pageY}`);
       console.log('mouseState: ' + JSON.stringify(mouseState));
       return;
@@ -38,8 +38,8 @@ const MouseHandler: react.FC<MouseHandlerProps> = (
   };
 
   const mouseDownHandler = (event: any) => {
-    genericHandler(event);
     event.preventDefault();
+    genericHandler(event);
     setMouseState({
       down: true,
       starting: { x: event.pageX, y: event.pageY },
@@ -57,8 +57,8 @@ const MouseHandler: react.FC<MouseHandlerProps> = (
     if (mouseState.down) {
       genericHandler(event);
       props.updateShift({
-        x: mouseState.starting.x - event.pageX,
-        y: mouseState.starting.y - event.pageY,
+        x: event.pageX - mouseState.starting.x,
+        y: event.pageY - mouseState.starting.y,
       });
       setMouseState({
         down: true,
@@ -75,13 +75,19 @@ const MouseHandler: react.FC<MouseHandlerProps> = (
     [mouseState.down]
   );
 
+  const doubleClickHandler = (event: any) => {
+    genericHandler(event);
+    props.updateZoom(2, { x: event.pageX, y: event.pageY });
+  };
+
   return (
     <div
-      className='viewport'
+      className='viewport mouse-handler'
       onMouseDown={mouseDownHandler}
       onMouseMove={throtteledMouseMoveHandler}
       onMouseUp={mouseUpHandler}
       onMouseLeave={mouseLeaveHandler}
+      onDoubleClick={doubleClickHandler}
     >
       {props.children}
     </div>

map/src/components/single-touch-handler.tsx

@@ -64,8 +64,8 @@ const SingleTouchHandler: react.FC<SingleTouchHandlerProps> = (
       if (event.touches.length === 1) {
         genericHandler(event);
         props.updateShift({
-          x: touchState.touch.x - event.touches[0].pageX,
-          y: touchState.touch.y - event.touches[0].pageY,
+          x:  event.touches[0].pageX - touchState.touch.x,
+          y:  event.touches[0].pageY - touchState.touch.y,
         });
         setTouchState({
           state: 'pointer',
@@ -85,7 +85,7 @@ const SingleTouchHandler: react.FC<SingleTouchHandlerProps> = (
 
   return (
     <div
-      className='viewport'
+      className='viewport single-touch-handler'
       onTouchStart={touchStartHandler}
       onTouchMove={throtteledTouchMoveHandler}
       onTouchEnd={touchEndHandler}

map/src/components/viewport.tsx

@@ -41,22 +41,18 @@ const Viewport: react.FC<ViewportProps> = (props: ViewportProps) => {
 
   const updateZoom = (zoomFactor: number, center: Point) => {
     const newZoom = zoom * zoomFactor;
-    setZoom(newZoom);
-    setShift({
-      x: shift.x + center.x / zoom - center.x / newZoom,
-      y: shift.y + center.y / zoom - center.y / newZoom,
+    updateShift({
+      x: (shift.x - center.x) * (zoomFactor - 1),
+      y: (shift.y - center.y) * (zoomFactor - 1),
     });
-    //   setShift({
-    //     x: shift.x + 1440 / 2 / zoom - window.innerWidth / 2 / newZoom,
-    //     y: shift.y + 2904 / 2 / zoom - window.innerHeight / 2 / newZoom,
-    //   });
+    setZoom(newZoom);
   };
 
   return (
     <div className='viewport'>
-      <MouseHandler updateShift={updateShift}>
+      <MouseHandler updateShift={updateShift} updateZoom={updateZoom}>
         <SingleTouchHandler updateShift={updateShift}>
-          <DoubleTouchHandler updateZoom={updateZoom}>
+          <DoubleTouchHandler updateZoom={updateZoom} updateShift={updateShift}>
             <Layer shift={shift} zoom={zoom}>
               {props.children}
             </Layer>