`一、前言`

最近有一个需求是修改默认的照片尺寸，这篇文章就总结一下Camara 选择默认的拍照尺寸的逻辑吧。

`二、定位代码`

`2.1、根据“照片大小” text 可以定位到布局文件 picturesize_preference.xml.`

代码路径:
android\vendor\mediatek\proprietary\packages\apps\Camera2\feature\setting\picturesize\res\xml\picturesize_preference.xml`**

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"><com.mediatek.camera.common.preference.Preferenceandroid:key="key_picture_size"android:title="@string/pref_camera_picturesize_title"android:persistent="false"android:order="40"/>
</PreferenceScreen>

Java 引用文件为:
代码路径: android\vendor\mediatek\proprietary\packages\apps\Camera2\feature\setting\picturesize\src\com\mediatek\camera\feature\setting\picturesize\PictureSizeSettingView.java

`三、流程逻辑分析`

`3.1、PictureSizeSettingView 照片尺寸列表值的初始化`

PictureSizeSettingView 的 setEntryValues 是传入照片尺寸列表的,这里是在其他地方调用传入值得。
代码路径: android\vendor\mediatek\proprietary\packages\apps\Camera2\feature\setting\picturesize\src\com\mediatek\camera\feature\setting\picturesize\PictureSizeSettingView.java

/*** Set the picture sizes supported.** @param entryValues The picture sizes supported.*/public void setEntryValues(List<String> entryValues) {mEntryValues = entryValues;}

`3.2、PictureSize.java 设置默认尺寸和可选尺寸`

全局搜一下可以发现是在PictureSize.java 中传入EntryValue的
代码路径: vendor/mediatek/proprietary/packages/apps/Camera2/feature/setting/picturesize/src/com/mediatek/camera/feature/setting/picturesize/PictureSize.java

总结一下流程:

1、获取屏幕的尺寸来计算出宽高比作为全屏的宽高比。
2、获取Sensor 传上来的可支持的照片尺寸supportedPictureSize。
3、从supportedPictureSize这里遍历选出可以用的尺寸里面最接近全屏宽高比的尺寸。
4、将全屏宽高比里面尺寸作为默认选中的尺寸。

    /*** Invoked after setting's all values are initialized.** @param supportedPictureSize Picture sizes which is supported in current platform.*/public void onValueInitialized(List<String> supportedPictureSize) {LogHelper.d(TAG, "[onValueInitialized], supportedPictureSize:" + supportedPictureSize);//1、这里获取屏幕的尺寸来计算出宽高比作为全屏的宽高比。double fullRatio = PictureSizeHelper.findFullScreenRatio(mActivity);List<Double> desiredAspectRatios = new ArrayList<>();desiredAspectRatios.add(fullRatio);desiredAspectRatios.add(PictureSizeHelper.RATIO_4_3);PictureSizeHelper.setDesiredAspectRatios(desiredAspectRatios);PictureSizeHelper.setFilterParameters(DEGRESSIVE_RATIO, MAX_COUNT);if (sFilterPictureSize) {supportedPictureSize = PictureSizeHelper.filterSizes(supportedPictureSize);LogHelper.d(TAG, "[onValueInitialized], after filter, supportedPictureSize = "+ supportedPictureSize);}.../***已省略部分代码......*/...//2、获取Sensor 传上来的可支持的照片尺寸supportedPictureSize。setSupportedPlatformValues(supportedPictureSize);setSupportedEntryValues(supportedPictureSize);setEntryValues(supportedPictureSize);refreshViewEntry();String valueInStore = mDataStore.getValue(getKey(), null, getStoreScope());Log.d("PictureSize 1,","onValueInitialized valueInStore="+valueInStore);if (valueInStore != null&& !supportedPictureSize.contains(valueInStore)) {LogHelper.d(TAG, "[onValueInitialized], value:" + valueInStore+ " isn't supported in current platform");valueInStore = null;mDataStore.setValue(getKey(), null, getStoreScope(), false);}if (valueInStore == null) {// Default picture size is the max full-ratio size.List<String> entryValues = getEntryValues();//3、这里遍历选出可以用的尺寸里面最接近全屏宽高比的尺寸。for (String value : entryValues) {if (PictureSizeHelper.getStandardAspectRatio(value) == fullRatio) {valueInStore = value;break;}}}// If there is no full screen ratio picture size, use the first value in// entry values as the default value.if (valueInStore == null) {valueInStore = getEntryValues().get(0);}Log.d("PictureSize 2,","onValueInitialized valueInStore="+valueInStore);//4、将全屏宽高比里面尺寸作为默认选中的尺寸。setValue(valueInStore);}

`四、Any question ？`

1、全屏的宽高比如何计算的？
2、默认的尺寸如果全屏宽高比有好几个怎么选择？

`4.1、全屏的宽高比如何计算的`

在上面提到获取全屏宽高比的地方是 PictureSizeHelper.findFullScreenRatio

//1、这里获取屏幕的尺寸来计算出宽高比作为全屏的宽高比。double fullRatio = PictureSizeHelper.findFullScreenRatio(mActivity);

代码路径： android\vendor\mediatek\proprietary\packages\apps\Camera2\feature\setting\picturesize\src\com\mediatek\camera\feature\setting\picturesize\PictureSizeHelper.java

在这里可以很清楚的看到计算全屏宽高比的步骤。

1、首选通过Display获取屏幕的尺寸。
2、计算屏幕尺寸的宽高比。
3、根据绝对值函数选取最靠近屏幕宽高比的数值作为全屏宽高比。

   /*** Compute full screen aspect ratio.** @param context The instance of {@link Context}.* @return The full screen aspect ratio.*/public static double findFullScreenRatio(Context context) {WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);//1、首选通过Display获取屏幕的尺寸。Display display = wm.getDefaultDisplay();DisplayMetrics dm = new DisplayMetrics();display.getRealMetrics(dm);int width = Math.max(dm.widthPixels, dm.heightPixels);int height = Math.min(dm.widthPixels, dm.heightPixels);//2、计算屏幕尺寸的宽高比。double displayRatio = (double) width / (double) height;Log.d("PictureSizeHelper",",findFullScreenRatio width="+width+",height="+height+",displayRatio="+displayRatio);double find = RATIO_4_3;//3、根据绝对值函数选取最靠近屏幕宽高比的数值作为全屏宽高比。for (int i = 0; i < RATIOS.length; i++) {double ratio = RATIOS[i];if (Math.abs(ratio - displayRatio) < Math.abs(find - displayRatio)) {find = ratio;}}return find;}

`4.2、默认的尺寸如果全屏宽高比有好几个怎么选择。`

在PictureSize中的 onValueInitialized方法中不考虑各个MODE功能的情况下，根据先来后到原则，最先匹配上全屏宽高比的尺寸作为默认选中的尺寸。看到这里有点失望，本来以为会比较一下比如16:9里面选择最大的作为默认尺寸。

if (valueInStore == null) {// Default picture size is the max full-ratio size.List<String> entryValues = getEntryValues();for (String value : entryValues) {if (PictureSizeHelper.getStandardAspectRatio(value) == fullRatio) {valueInStore = value;break;}}

`五、定制将支持照片尺寸里面选择最大的作为默认尺寸。`

diff --git a/vendor/mediatek/proprietary/packages/apps/Camera2/feature/setting/picturesize/src/com/mediatek/camera/feature/setting/picturesize/PictureSize.java b/vendor/mediatek/proprietary/packages/apps/Camera2/feature/setting/picturesize/src/com/mediatek/camera/feature/setting/picturesize/PictureSize.java
index f3a3954b727..77247a04614 100755
--- a/vendor/mediatek/proprietary/packages/apps/Camera2/feature/setting/picturesize/src/com/mediatek/camera/feature/setting/picturesize/PictureSize.java
+++ b/vendor/mediatek/proprietary/packages/apps/Camera2/feature/setting/picturesize/src/com/mediatek/camera/feature/setting/picturesize/PictureSize.java
@@ -48,6 +48,8 @@ import com.mediatek.camera.portability.SystemProperties;import java.util.ArrayList;import java.util.List;
+import android.util.Log;
+/*** Picture size setting item.
@@ -114,6 +116,7 @@ public class PictureSize extends SettingBase implementsmSettingView.setEntryValues(getEntryValues());mSettingView.setEnabled(getEntryValues().size() > 1);}
+        }@Override
@@ -245,6 +248,7 @@ public class PictureSize extends SettingBase implementsrefreshViewEntry();String valueInStore = mDataStore.getValue(getKey(), null, getStoreScope());
+        Log.d("PictureSize 1,","onValueInitialized valueInStore="+valueInStore);if (valueInStore != null&& !supportedPictureSize.contains(valueInStore)) {LogHelper.d(TAG, "[onValueInitialized], value:" + valueInStore
@@ -254,19 +258,23 @@ public class PictureSize extends SettingBase implements}if (valueInStore == null) {// Default picture size is the max full-ratio size.
-            List<String> entryValues = getEntryValues();
+            //add begin...
+            /*List<String> entryValues = getEntryValues();for (String value : entryValues) {if (PictureSizeHelper.getStandardAspectRatio(value) == fullRatio) {valueInStore = value;break;}
-            }
+            }*/
+            valueInStore =PictureSizeHelper.getMaxPictureSize(getEntryValues());
+            //add end..}// If there is no full screen ratio picture size, use the first value in// entry values as the default value.if (valueInStore == null) {valueInStore = getEntryValues().get(0);}
+        Log.d("PictureSize 2,","onValueInitialized valueInStore="+valueInStore);setValue(valueInStore);}@@ -295,6 +303,7 @@ public class PictureSize extends SettingBase implementssetEntryValues(supportedPictureSize);refreshViewEntry();setValue(forceChosenPictureSize);
+        Log.d("PictureSize,","onValueInitialized forceChosenPictureSize="+forceChosenPictureSize);mDataStore.setValue(getKey(), getValue(), getStoreScope(), false);LogHelper.d(TAG, "[onValueInitialized] -");}
diff --git a/vendor/mediatek/proprietary/packages/apps/Camera2/feature/setting/picturesize/src/com/mediatek/camera/feature/setting/picturesize/PictureSizeHelper.java b/vendor/mediatek/pro
prietary/packages/apps/Camera2/feature/setting/picturesize/src/com/mediatek/camera/feature/setting/picturesize/PictureSizeHelper.java
index d2f9ec9a33b..06cfe7713b9 100755
--- a/vendor/mediatek/proprietary/packages/apps/Camera2/feature/setting/picturesize/src/com/mediatek/camera/feature/setting/picturesize/PictureSizeHelper.java
+++ b/vendor/mediatek/proprietary/packages/apps/Camera2/feature/setting/picturesize/src/com/mediatek/camera/feature/setting/picturesize/PictureSizeHelper.java
@@ -57,6 +57,7 @@ import java.util.HashMap;import java.util.LinkedList;import java.util.List;import java.util.Map;
+import android.util.Log;/*** Picture size helper to provide util methods.
@@ -109,7 +110,7 @@ public class PictureSizeHelper {int width = Math.max(dm.widthPixels, dm.heightPixels);int height = Math.min(dm.widthPixels, dm.heightPixels);double displayRatio = (double) width / (double) height;
-
+        Log.d("PictureSizeHelper",",findFullScreenRatio width="+width+",height="+height+",displayRatio="+displayRatio);double find = RATIO_4_3;for (int i = 0; i < RATIOS.length; i++) {double ratio = RATIOS[i];
@@ -279,6 +280,23 @@ public class PictureSizeHelper {return ratio;}+    //add begin.
+    public static String getMaxPictureSize(List<String> supportedEntryValues){
+        int temp=0;
+        int maxSize=0;
+        int maxIndex=0;
+        for (int i=0;i< supportedEntryValues.size();i++) {
+            Size size = valueToSize(supportedEntryValues.get(i));
+            temp = size.width * size.height;
+            if (temp > maxSize) {
+                maxSize = temp;
+                maxIndex = i;
+            }
+        }
+        return supportedEntryValues.get(maxIndex);
+    }
+    //add end.
+private static List<Size> pickUpToThree(List<Size> sizes) {if (sDegressiveRatio == 0 || sMaxCount == 0) {return sizes;

`六、结语`

Okay,So much for this !

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