Initial import

resources/imageview_fragment.gles

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+precision highp float;
+
+varying vec2 uv;
+varying vec2 position_background;
+uniform sampler2D image;
+uniform vec4 background_color;
+
+void main() {
+    vec2 frac = position_background - floor(position_background);
+    float checkerboard = ((frac.x > .5) == (frac.y > .5)) ? 0.4 : 0.5;
+
+    vec4 background = (1.0 - background_color.a) * vec4(vec3(checkerboard), 1.0) +
+                             background_color.a * vec4(background_color.rgb, 1.0);
+
+    vec4 value = texture2D(image, uv);
+    gl_FragColor = (1.0 - value.a) * background + value.a * vec4(value.rgb, 1.0);
+}