Reduced the complexity of layers composition.

This change also refactors the code base a bit by moving classes out of
OpenGLRenderer into separate headers/implementations. This makes the code
more manageable.

This change also adds documentation for implementation methods. The
undocumented methods are simply Skia's Canvas methods.

Change-Id: I54c68b443580a0129251dddc1a7ac95813d5289e

1 files changed, 145 insertions, 0 deletions

diff --git a/libs/hwui/Snapshot.h b/libs/hwui/Snapshot.h
new file mode 100644
index 0000000..9a9be2d
--- /dev/null
+++ b/libs/hwui/Snapshot.h
@@ -0,0 +1,145 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_UI_SNAPSHOT_H
+#define ANDROID_UI_SNAPSHOT_H
+
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+#include <utils/RefBase.h>
+
+#include "Matrix.h"
+#include "Rect.h"
+
+namespace android {
+namespace uirenderer {
+
+/**
+ * A snapshot holds information about the current state of the rendering
+ * surface. A snapshot is usually created whenever the user calls save()
+ * and discarded when the user calls restore(). Once a snapshot is created,
+ * it can hold information for deferred rendering.
+ *
+ * Each snapshot has a link to a previous snapshot, indicating the previous
+ * state of the renderer.
+ */
+class Snapshot: public LightRefBase<Snapshot> {
+public:
+    Snapshot() {
+    }
+
+    /**
+     * Copies the specified snapshot. Only the transform and clip rectangle
+     * are copied. The layer information is set to 0 and the transform is
+     * assumed to be dirty. The specified snapshot is stored as the previous
+     * snapshot.
+     */
+    Snapshot(const sp<Snapshot> s):
+            transform(s->transform),
+            clipRect(s->clipRect),
+            flags(kFlagDirtyTransform),
+            previous(s),
+            layer(0.0f, 0.0f, 0.0f, 0.0f),
+            texture(0),
+            fbo(0),
+            alpha(255) {
+    }
+
+    /**
+     * Various flags set on #flags.
+     */
+    enum Flags {
+        /**
+         * Indicates that the clip region was modified. When this
+         * snapshot is restored so must the clip.
+         */
+        kFlagClipSet = 0x1,
+        /**
+         * Indicates that the snapshot holds new transform
+         * information.
+         */
+        kFlagDirtyTransform = 0x2,
+        /**
+         * Indicates that this snapshot was created when saving
+         * a new layer.
+         */
+        kFlagIsLayer = 0x4,
+    };
+
+    /**
+     * Returns the current clip region mapped by the current transform.
+     */
+    const Rect& getMappedClip() {
+        if (flags & kFlagDirtyTransform) {
+            flags &= ~kFlagDirtyTransform;
+            mappedClip.set(clipRect);
+            transform.mapRect(mappedClip);
+        }
+        return mappedClip;
+    }
+
+    /**
+     * Local transformation. Holds the current translation, scale and
+     * rotation values.
+     */
+    mat4 transform;
+
+    /**
+     * Current clip region.
+     */
+    Rect clipRect;
+
+    /**
+     * Dirty flags.
+     */
+    int flags;
+
+    /**
+     * Previous snapshot.
+     */
+    sp<Snapshot> previous;
+
+    /**
+     * Coordinates of the layer corresponding to this snapshot.
+     * Only set when the flag kFlagIsLayer is set.
+     */
+    Rect layer;
+    /**
+     * Name of the texture used to render the layer.
+     * Only set when the flag kFlagIsLayer is set.
+     */
+    GLuint texture;
+    /**
+     * Name of the FBO used to render the layer.
+     * Only set when the flag kFlagIsLayer is set.
+     */
+    GLuint fbo;
+    /**
+     * Opacity of the layer.
+     * Only set when the flag kFlagIsLayer is set.
+     */
+    float alpha;
+
+private:
+    // Clipping rectangle mapped with the transform
+    Rect mappedClip;
+}; // class Snapshot
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_UI_SNAPSHOT_H