add support for setting the background color

this is a revision of the h/w composer API. This change
is binary backward compatible.

Change-Id: Id4cf43447594db9049f7e2c44ea08157ca725129

include/hardware/hwcomposer.h

@@ -28,7 +28,7 @@ __BEGIN_DECLS
 
 /*****************************************************************************/
 
-#define HWC_API_VERSION 1
+#define HWC_API_VERSION HARDWARE_DEVICE_API_VERSION(0,2)
 
 /**
  * The id of this module
@@ -91,6 +91,10 @@ enum {
 
     /* this layer will be handled in the HWC */
     HWC_OVERLAY = 1,
+
+    /* this is the background layer. it's used to set the background color.
+     * there is only a single background layer */
+    HWC_BACKGROUND = 2,
 };
 
 /*
@@ -123,6 +127,12 @@ enum {
     HWC_TRANSFORM_ROT_270 = HAL_TRANSFORM_ROT_270,
 };
 
+/* attributes queriable with query() */
+enum {
+    /* must return 1 if the background layer is supported, 0 otherwise */
+    HWC_BACKGROUND_LAYER_SUPPORTED      = 0,
+};
+
 typedef struct hwc_rect {
     int left;
     int top;
@@ -135,12 +145,29 @@ typedef struct hwc_region {
     hwc_rect_t const* rects;
 } hwc_region_t;
 
+typedef struct hwc_color {
+    uint8_t r;
+    uint8_t g;
+    uint8_t b;
+    uint8_t a;
+} hwc_color_t;
+
 typedef struct hwc_layer {
     /*
-     * initially set to HWC_FRAMEBUFFER, indicates the layer will
+     * initially set to HWC_FRAMEBUFFER or HWC_BACKGROUND.
-     * be drawn into the framebuffer using OpenGL ES.
+     * HWC_FRAMEBUFFER
+     *   indicates the layer will be drawn into the framebuffer
+     *   using OpenGL ES.
      *   The HWC can toggle this value to HWC_OVERLAY, to indicate
      *   it will handle the layer.
+     *
+     * HWC_BACKGROUND
+     *   indicates this is a special "background"  layer. The only valid
+     *   field is backgroundColor. HWC_BACKGROUND can only be used with
+     *   HWC_API_VERSION >= 0.2
+     *   The HWC can toggle this value to HWC_FRAMEBUFFER, to indicate
+     *   it CANNOT handle the background color
+     *
      */
     int32_t compositionType;
 
@@ -150,6 +177,12 @@ typedef struct hwc_layer {
     /* see hwc_layer_t::flags above */
     uint32_t flags;
 
+    union {
+        /* color of the background.  hwc_color_t.a is ignored */
+        hwc_color_t backgroundColor;
+
+        struct {
+
             /* handle of buffer to compose. This handle is guaranteed to have been
              * allocated from gralloc using the GRALLOC_USAGE_HW_COMPOSER usage flag. If
              * the layer's handle is unchanged across two consecutive prepare calls and
@@ -179,6 +212,8 @@ typedef struct hwc_layer {
              * The visible region INCLUDES areas overlapped by a translucent layer.
              */
             hwc_region_t visibleRegionScreen;
+        };
+    };
 } hwc_layer_t;
 
 
@@ -333,7 +368,17 @@ typedef struct hwc_composer_device {
     void (*registerProcs)(struct hwc_composer_device* dev,
             hwc_procs_t const* procs);
 
-    void* reserved_proc[6];
+    /*
+     * This hook is OPTIONAL.
+     *
+     * Used to retrieve information about the h/w composer
+     *
+     * Returns 0 on success or -errno on error.
+     */
+    int (*query)(struct hwc_composer_device* dev, int what, int* value);
+
+
+    void* reserved_proc[5];
 
 } hwc_composer_device_t;