1 files changed, 115 insertions, 0 deletions
diff --git a/src/com/android/camera/ShutterButton.java b/src/com/android/camera/ShutterButton.java
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+++ b/src/com/android/camera/ShutterButton.java
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+/*
+ * Copyright (C) 2008 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.
+ */
+
+package com.android.camera;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.widget.ImageView;
+
+/**
+ * A button designed to be used for the on-screen shutter button.
+ * It's currently an ImageView that can call a delegate when the pressed state changes.
+ */
+public class ShutterButton extends ImageView {
+    /**
+     * Interface definition for a callback to be invoked when a ModeButton's pressed state changes.
+     */
+    public interface OnShutterButtonListener {
+        /**
+         * Called when a ShutterButton has been pressed.
+         *
+         * @param b The ShutterButton that was pressed.
+         */
+        void onShutterButtonFocus(ShutterButton b, boolean pressed);
+        void onShutterButtonClick(ShutterButton b);
+    }
+
+    private OnShutterButtonListener mListener;
+    private boolean mOldPressed;
+
+    public ShutterButton(Context context) {
+        super(context);
+    }
+
+    public ShutterButton(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public ShutterButton(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+    }
+
+    public void setOnShutterButtonListener(OnShutterButtonListener listener) {
+        mListener = listener;
+    }
+
+    /**
+     * Hook into the drawable state changing to get changes to isPressed -- the
+     * onPressed listener doesn't always get called when the pressed state changes.
+     */
+    @Override
+    protected void drawableStateChanged() {
+        super.drawableStateChanged();
+        final boolean pressed = isPressed();
+        if (pressed != mOldPressed) {
+            if (!pressed) {
+                // When pressing the physical camera button the sequence of events is:
+                //    focus pressed, optional camera pressed, focus released.
+                // We want to emulate this sequence of events with the shutter button.
+                // When clicking using a trackball button, the view system changes
+                // the the drawable state before posting click notification, so the
+                // sequence of events is:
+                //    pressed(true), optional click, pressed(false)
+                // When clicking using touch events, the view system changes the
+                // drawable state after posting click notification, so the sequence of
+                // events is:
+                //    pressed(true), pressed(false), optional click
+                // Since we're emulating the physical camera button, we want to have the
+                // same order of events. So we want the optional click callback to be delivered
+                // before the pressed(false) callback.
+                //
+                // To do this, we delay the posting of the pressed(false) event slightly by
+                // pushing it on the event queue. This moves it after the optional click
+                // notification, so our client always sees events in this sequence:
+                //     pressed(true), optional click, pressed(false)
+                post(new Runnable() {
+                    public void run() {
+                        callShutterButtonFocus(pressed);
+                    }
+                });
+            } else {
+                callShutterButtonFocus(pressed);
+            }
+            mOldPressed = pressed;
+        }
+    }
+
+    private void callShutterButtonFocus(boolean pressed) {
+        if (mListener != null) {
+            mListener.onShutterButtonFocus(this, pressed);
+        }
+    }
+
+    @Override
+    public boolean performClick() {
+        boolean result = super.performClick();
+        if (mListener != null) {
+            mListener.onShutterButtonClick(this);
+        }
+        return result;
+    }
+}