1 files changed, 91 insertions, 0 deletions
diff --git a/misc/openlayers/examples/canvas-inspector.js b/misc/openlayers/examples/canvas-inspector.js
new file mode 100644
index 0000000..064b4d5
--- /dev/null
+++ b/misc/openlayers/examples/canvas-inspector.js
@@ -0,0 +1,91 @@
+
+var features = [
+
+    new OpenLayers.Feature.Vector(
+        OpenLayers.Geometry.fromWKT(
+            "LINESTRING(-90 90, 90 -90)"
+        ),
+        {color: "#0f0000"}
+    ),
+    
+    new OpenLayers.Feature.Vector(
+        OpenLayers.Geometry.fromWKT(
+            "LINESTRING(100 50, -100 -50)"
+        ),
+        {color: "#00ff00"}
+    )
+
+];
+
+var layer = new OpenLayers.Layer.Vector(null, {
+    styleMap: new OpenLayers.StyleMap({
+        strokeWidth: 3,
+        strokeColor: "${color}"
+    }),
+    isBaseLayer: true,
+    renderers: ["Canvas"],
+    rendererOptions: {hitDetection: true}
+});
+layer.addFeatures(features);
+
+var map = new OpenLayers.Map({
+    div: "map",
+    layers: [layer],
+    center: new OpenLayers.LonLat(0, 0),
+    zoom: 0
+});
+
+var xOff = 2, yOff = 2;
+
+var rows = 1 + (2 * yOff);
+var cols = 1 + (2 * xOff);
+
+var template = new jugl.Template("template");
+template.process({
+    clone: true,
+    parent: "inspector",
+    context: {
+        rows: rows,
+        cols: cols
+    }
+});
+
+function isDark(r, g, b, a) {
+    a = a / 255;
+    var da = 1 - a;
+    // convert color values to decimal (assume white background)
+    r = (a * r / 255) + da;
+    g = (a * g / 255) + da;
+    b = (a * b / 255) + da;
+    // use w3C brightness measure
+    var brightness = (r * 0.299) + (g * 0.587) + (b * 0.144);
+    return brightness < 0.5;
+}
+
+var context = layer.renderer.canvas; //layer.renderer.hitContext;
+var size = map.getSize();
+map.events.on({
+    mousemove: function(event) {
+        var x = event.xy.x - 1; // TODO: fix this elsewhere
+        var y = event.xy.y;
+        if ((x >= xOff) && (x < size.w - xOff) && (y >= yOff) && (y < size.h - yOff)) {
+            var data = context.getImageData(x - xOff, y - yOff, rows, cols).data;
+            var offset, red, green, blue, alpha, cell;
+            for (var i=0; i<cols; ++i) {
+                for (var j=0; j<rows; ++j) {
+                    offset = (i * 4) + (j * 4 * cols);
+                    red = data[offset];
+                    green = data[offset + 1];
+                    blue = data[offset + 2];
+                    alpha = data[offset + 3];
+                    cell = document.getElementById("c" + i + "r" + j);
+                    cell.innerHTML = "R: " + red + "<br>G: " + green + "<br>B: " + blue + "<br>A: " + alpha;
+                    cell.style.backgroundColor = "rgba(" + red + ", " + green + ", " + blue + ", " + (alpha / 255) + ")";
+                    cell.style.color = isDark(red, green, blue, alpha) ? "#ffffff" : "#000000";
+                }
+            }
+        }
+    }
+});
+
+