android相机固定焦距 安卓手机相机对焦设置 |
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android相机固定焦距 安卓手机相机对焦设置
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一、简介 本篇文章为对焦系列文章的第一篇：主要讲解UI坐标系和相机坐标系。后续其他相关文章如下： 二、对焦和区域测光日常使用照片拍照有如下几种场景： 默认自动对焦【视频、拍照连续对焦】点击某一个区域单次对焦从 Android 4.0（API 级别 14）开始，在拍摄图片或视频时，能够在图片中指定区域，并将这些值传递给相机硬件用于控制固定区域进行对焦和测光。区域对焦和区域测光可通过Parameters对应的Key进行设置。 2.1 区域相关设置代码/** *Gets the current focus areas. Camera driver uses the areas to decide * focus. * *Before using this API or {@link #setFocusAreas(List)}, apps should * call {@link #getMaxNumFocusAreas()} to know the maximum number of * focus areas first. If the value is 0, focus area is not supported. * *Each focus area is a rectangle with specified weight. The direction * is relative to the sensor orientation, that is, what the sensor sees. * The direction is not affected by the rotation or mirroring of * {@link #setDisplayOrientation(int)}. Coordinates of the rectangle * range from -1000 to 1000. (-1000, -1000) is the upper left point. * (1000, 1000) is the lower right point. The width and height of focus * areas cannot be 0 or negative. * *The weight must range from 1 to 1000. The weight should be * interpreted as a per-pixel weight - all pixels in the area have the * specified weight. This means a small area with the same weight as a * larger area will have less influence on the focusing than the larger * area. Focus areas can partially overlap and the driver will add the * weights in the overlap region. * *A special case of a {@code null} focus area list means the driver is * free to select focus targets as it wants. For example, the driver may * use more signals to select focus areas and change them * dynamically. Apps can set the focus area list to {@code null} if they * want the driver to completely control focusing. * *Focus areas are relative to the current field of view * ({@link #getZoom()}). No matter what the zoom level is, (-1000,-1000) * represents the top of the currently visible camera frame. The focus * area cannot be set to be outside the current field of view, even * when using zoom. * *Focus area only has effect if the current focus mode is * {@link #FOCUS_MODE_AUTO}, {@link #FOCUS_MODE_MACRO}, * {@link #FOCUS_MODE_CONTINUOUS_VIDEO}, or * {@link #FOCUS_MODE_CONTINUOUS_PICTURE}. * * @return a list of current focus areas */ public List getFocusAreas() { return splitArea(get(KEY_FOCUS_AREAS)); } public void setFocusAreas(List focusAreas) { set(KEY_FOCUS_AREAS, focusAreas); } /** * Gets the maximum number of focus areas supported. This is the maximum * length of the list in {@link #setFocusAreas(List)} and * {@link #getFocusAreas()}. * * @return the maximum number of focus areas supported by the camera. * @see #getFocusAreas() */ public int getMaxNumFocusAreas() { return getInt(KEY_MAX_NUM_FOCUS_AREAS, 0); }分析： getMaxNumFocusAreas()获取当前Camera Lens支持对焦区域的个数。如果为0则表示不支持对焦固定的输入区域通过设置focus-area来控制Camera Lens针对特定的区域进行对焦focus-area是一个rect。范围为【-1000，1000】，weight：【1，1000】，可参看Camera1源码分析【Java层】【2.1】 setFocusAreas(null) -> 交给Camera自己控制和zoom值没关系。区域对应的始终是zoom=1.0x的画面。详细可参看后续Camera1对焦之zoom2.2 代码举例官网示例代码如下： // Create an instance of Camera // Create an instance of Camera camera = getCameraInstance(); // set Camera parameters Camera.Parameters params = camera.getParameters(); if (params.getMaxNumMeteringAreas() > 0){ // check that metering areas are supported List meteringAreas = new ArrayList(); Rect areaRect1 = new Rect(-100, -100, 100, 100); // specify an area in center of image meteringAreas.add(new Camera.Area(areaRect1, 600)); // set weight to 60% Rect areaRect2 = new Rect(800, -1000, 1000, -800); // specify an area in upper right of image meteringAreas.add(new Camera.Area(areaRect2, 400)); // set weight to 40% params.setMeteringAreas(meteringAreas); } if (params.getMaxNumFocusAreas() > 0){ // check that focus areas are supported List focusAreas = new ArrayList(); Rect areaRect1 = new Rect(-100, -100, 100, 100); // specify an area in center of image focusAreas.add(new Camera.Area(areaRect1, 600)); // set weight to 60% Rect areaRect2 = new Rect(800, -1000, 1000, -800); // specify an area in upper right of image focusAreas.add(new Camera.Area(areaRect2, 400)); // set weight to 40% params.setFocusAreas(focusAreas); } camera.setParameters(params);分析 首先通过getMaxNumFocusAreas()和getMaxNumMeteringAreas()来判断是否支持区域对焦和区域测光。设置了2个不同权重的Rect进行区域对焦和区域测光。三、不同坐标系3.1 相机坐标系图一
图一中，给出了相机的坐标系，注意这里是横屏的。相机的坐标系中值的范围是[-1000，1000]。因此在左上角是[-1000, 1000]。右下角是[1000,1000]。 图一中也给出了要设置的rect(333,333,667,667)。如果调用代码1则会在该区域对焦。如果调用代码2，则会在该区域测光AE 代码1: ************ params.setFocusAreas(new Camera.Area(rect)) 代码2: ************ params.setMeteringAreas(new Camera.Area(rect))3.2 UI坐标系3.1我们阐述了相机坐标系，但是图是横的，实际使用手机，大部分的场景是竖直的。因此我们参看图二。 图二
图二有左右2个图，不同的orientation。这里一定要明白： 相机的输出流会和后置Camera Lens有90的的夹角；和前置Camera Lens有270度的夹角 因此在右侧整的的UI坐标系中，左上角是(0,0)，右下角是(mPreviewWidth, mPreviewHeight)，orientation：90度。 那么对应到相机的坐标系中， 3.1 横屏：左上角是(-1000, -1000)，右下角是(1000,1000)。竖直：右上角是(-1000, -1000)，左下角是(1000,1000)。所以当点击某个区域对焦时，需要做的工作就是：把UI坐标系的点坐标转换成为相机坐标系下的点坐标对应的rect区域 四、总结这里总结一下【手机竖直】 ： UI坐标系：左上角是(0,0)，右下角是(mPreviewWidth, mPreviewHeight)相机坐标系：右上角是(-1000, -1000)，左下角是(1000,1000)点击对焦测光：Point(x, y)[ui] -> Point(x, y)[camera] -> Rect(l, t, r, b)[camera]具体的点击对焦测光计算算法如下： 获取点击对应的Point(x, y)Point(x, y)根据相机的orient方向，来判断是否进行x, y互换【后置从UI到相机参考系需要逆时针旋转-90度】Point(x, y) 从(0, 0, mPreviewWidth, mPreviewHeight) => (-1000, -1000, 1000, 1000)Point(x, y) [camera] 根据AspectRatio和区域Size => Rect[Camera]下一篇将讲解Camera1对焦区域具体的计算算法和相关代码。
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