first semi-working example

src/components/Canvas.vue

@@ -32,7 +32,6 @@
     },
     methods: {
       loadImage: function (imageUrl) {
-        console.log(imageUrl + '!!!')
         this.image = new Image()
         this.image.onload = () => {
           this.imageLoaded = true

src/components/Player.vue

@@ -3,6 +3,10 @@
     <div id="player-canvas-container">
       <canvas ref="canvas" id="player-canvas" :height="height" :width="width"></canvas>
     </div>
+    <div>
+      <label for="posSlider">POS</label>
+      <input type="range" min="0" :max="frames - 1" value="0" class="slider" id="posSlider" v-model="position">
+    </div>
     <button @click="playPause">{{buttonLabel}}</button>
   </div>
 </template>
@@ -18,7 +22,17 @@
       return {
         image: null,
         buttonLabel: 'PLAY',
-        playing: false
+        playing: false,
+        position: 0,
+        tmp_ctx: null,
+        animation_id: null
+      }
+    },
+    computed: {
+      frames: function () {
+        if (this.image === null) return 0
+        return Math.ceil(this.image.width / this.width) *
+          Math.ceil(this.image.height / this.height)
       }
     },
     mounted: function () {
@@ -37,14 +51,22 @@
         setTimeout(() => {
           this.clear('red')
         }, 0)
+      },
+      position: function () {
+        if (this.image === null) return
+        this.tmp_ctx = this.$refs.canvas.getContext('2d')
+        this.$render()
       }
     },
     methods: {
       playPause: function () {
         this.playing = !this.playing
         if (this.playing) {
+          this.tmp_ctx = this.$refs.canvas.getContext('2d')
+          this.animation_id = requestAnimationFrame(this.$render_advance)
           this.buttonLabel = 'STOP'
         } else {
+          cancelAnimationFrame(this.animation_id)
           this.buttonLabel = 'PLAY'
         }
       },
@@ -54,7 +76,20 @@
         ctx.fillRect(0, 0, parseInt(this.width), parseInt(this.height))
       },
       $render: function () {
-
+        let wb = Math.ceil(this.image.width / this.width)
+        let x = (this.position % wb) * this.width
+        let w = x + this.width < this.image.width ? this.width : this.image.width - x
+        let y = Math.floor(this.position / wb) * this.height
+        let h = y + this.height < this.image.height ? this.height : this.image.height - y
+        if (w !== this.width || h !== this.height) this.clear('black')
+        this.tmp_ctx.drawImage(this.image, x, y, w, h, 0, 0, w, h)
+      },
+      $render_advance: function () {
+        this.$render()
+        if (this.position < this.frames) {
+          this.position += 1
+          requestAnimationFrame(this.$render_advance)
+        }
       }
     }
   }

src/components/Sidebar.vue

@@ -35,7 +35,7 @@
     </div>
     <div>
       <label for="fps">FPS: </label>
-      <input class="spinBox" id="fps" v-model="fps" type="number" min="1" max="60" step="1" value="60">
+      <input class="spinBox" id="fps" v-model="fps" type="number" min="1" max="60" step="1" value="60" disabled>
     </div>
     <div>
       <label>Est. length: {{length}}</label>