效果图如下：
一、为预览控件设置圆角
为控件设置viewoutlineprovider
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public roundtextureview(context context, attributeset attrs) {
super(context, attrs);
setoutlineprovider(new viewoutlineprovider() {
@override
public void getoutline(view view, outline outline) {
rect rect = new rect(0, 0, view.getmeasuredwidth(), view.getmeasuredheight());
outline.setroundrect(rect, radius);
}
});
setcliptooutline(true);
}
在需要时修改圆角值并更新
public void setradius(int radius) {
this.radius = radius;
}
public void turnround() {
invalidateoutline();
}
即可根据设置的圆角值更新控件显示的圆角大小。当控件为正方形，且圆角值为边长的一半，显示的就是圆形。
二、实现正方形预览
1. 设备支持1:1预览尺寸
首先介绍一种简单但是局限性较大的实现方式：将相机预览尺寸和预览控件的大小都调整为1:1。
一般android设备都支持多种预览尺寸，以samsung tab s3为例
在使用camera api时，其支持的预览尺寸如下：
2019-08-02 13:16:08.669 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 1920x1080 2019-08-02 13:16:08.669 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 1280x720 2019-08-02 13:16:08.669 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 1440x1080 2019-08-02 13:16:08.669 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 1088x1088 2019-08-02 13:16:08.670 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 1056x864 2019-08-02 13:16:08.670 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 960x720 2019-08-02 13:16:08.670 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 720x480 2019-08-02 13:16:08.670 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 640x480 2019-08-02 13:16:08.670 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 352x288 2019-08-02 13:16:08.670 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 320x240 2019-08-02 13:16:08.670 16407-16407/com.wsy.glcamerademo i/camerahelper: supportedpreviewsize: 176x144
其中1:1的预览尺寸为：1088x1088。
在使用camera2 api时，其支持的预览尺寸（其实也包含了picturesize）如下：
2019-08-02 13:19:24.980 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 4128x3096 2019-08-02 13:19:24.980 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 4128x2322 2019-08-02 13:19:24.980 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 3264x2448 2019-08-02 13:19:24.980 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 3264x1836 2019-08-02 13:19:24.980 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 3024x3024 2019-08-02 13:19:24.980 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 2976x2976 2019-08-02 13:19:24.980 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 2880x2160 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 2592x1944 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 2560x1920 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 2560x1440 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 2560x1080 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 2160x2160 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 2048x1536 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 2048x1152 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 1936x1936 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 1920x1080 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 1440x1080 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 1280x960 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 1280x720 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 960x720 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 720x480 2019-08-02 13:19:24.981 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 640x480 2019-08-02 13:19:24.982 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 320x240 2019-08-02 13:19:24.982 16768-16768/com.wsy.glcamerademo i/camera2helper: getbestsupportedsize: 176x144
其中1:1的预览尺寸为：3024x3024、2976x2976、2160x2160、1936x1936。
只要我们选择1:1的预览尺寸，再将预览控件设置为正方形，即可实现正方形预览；
再通过设置预览控件的圆角为边长的一半，即可实现圆形预览。2. 设备不支持1:1预览尺寸的情况
选择1:1预览尺寸的缺陷分析
分辨率局限性
上述说到，我们可以选择1:1的预览尺寸进行预览，但是局限性较高，
可选择范围都很小。如果相机不支持1:1的预览尺寸，这个方案就不可行了。
资源消耗
以samsung tab s3为例，该设备使用camera2 api时，支持的正方形预览尺寸都很大，在进行图像处理等操作时将占用较多系统资源。
处理不支持1:1预览尺寸的情况
添加一个1:1尺寸的viewgroup
将textureview放入viewgroup
设置textureview的margin值以达到显示中心正方形区域的效果
示意图
示例代码
//将预览控件和预览尺寸比例保持一致，避免拉伸
{
framelayout.layoutparams textureviewlayoutparams = (framelayout.layoutparams) textureview.getlayoutparams();
int newheight = 0;
int newwidth = textureviewlayoutparams.width;
//横屏
if (displayorientation % 180 == 0) {
newheight = textureviewlayoutparams.width * previewsize.height / previewsize.width;
}
//竖屏
else {
newheight = textureviewlayoutparams.width * previewsize.width / previewsize.height;
}
////当不是正方形预览的情况下，添加一层viewgroup限制view的显示区域
if (newheight != textureviewlayoutparams.height) {
insertframelayout = new roundframelayout(coverbyparentcameraactivity.this);
int sidelength = math.min(newwidth, newheight);
framelayout.layoutparams layoutparams = new framelayout.layoutparams(sidelength, sidelength);
insertframelayout.setlayoutparams(layoutparams);
framelayout parentview = (framelayout) textureview.getparent();
parentview.removeview(textureview);
parentview.addview(insertframelayout);
insertframelayout.addview(textureview);
framelayout.layoutparams newtextureviewlayoutparams = new framelayout.layoutparams(newwidth, newheight);
//横屏
if (displayorientation % 180 == 0) {
newtextureviewlayoutparams.leftmargin = ((newheight - newwidth) / 2);
}
//竖屏
else {
newtextureviewlayoutparams.topmargin = -(newheight - newwidth) / 2;
}
textureview.setlayoutparams(newtextureviewlayoutparams);
}
}
三、使用glsurfaceview进行自定义程度更高的预览
使用上面的方法操作已经可完成正方形和圆形预览，但是仅适用于原生相机，当我们的数据源并非是原生相机的情况时如何进行圆形预览？接下来介绍使用glsurfaceview显示nv21的方案，完全是自己实现预览数据的绘制。
1. glsurfaceview使用流程
opengl渲染yuv数据流程
其中的重点是渲染器（renderer）的编写，renderer的介绍如下：
/**
* a generic renderer interface.
* <p>
* the renderer is responsible for making opengl calls to render a frame.
* <p>
* glsurfaceview clients typically create their own classes that implement
* this interface, and then call {@link glsurfaceview#setrenderer} to
* register the renderer with the glsurfaceview.
* <p>
*
* <div class="special reference">
* <h3>developer guides</h3>
* <p>for more information about how to use opengl, read the
* <a href="{@docroot}guide/topics/graphics/opengl.html" rel="external nofollow" >opengl</a> developer guide.</p>
* </div>
*
* <h3>threading</h3>
* the renderer will be called on a separate thread, so that rendering
* performance is decoupled from the ui thread. clients typically need to
* communicate with the renderer from the ui thread, because that's where
* input events are received. clients can communicate using any of the
* standard java techniques for cross-thread communication, or they can
* use the {@link glsurfaceview#queueevent(runnable)} convenience method.
* <p>
* <h3>egl context lost</h3>
* there are situations where the egl rendering context will be lost. this
* typically happens when device wakes up after going to sleep. when
* the egl context is lost, all opengl resources (such as textures) that are
* associated with that context will be automatically deleted. in order to
* keep rendering correctly, a renderer must recreate any lost resources
* that it still needs. the {@link #onsurfacecreated(gl10, eglconfig)} method
* is a convenient place to do this.
*
*
* @see #setrenderer(renderer)
*/
public interface renderer {
/**
* called when the surface is created or recreated.
* <p>
* called when the rendering thread
* starts and whenever the egl context is lost. the egl context will typically
* be lost when the android device awakes after going to sleep.
* <p>
* since this method is called at the beginning of rendering, as well as
* every time the egl context is lost, this method is a convenient place to put
* code to create resources that need to be created when the rendering
* starts, and that need to be recreated when the egl context is lost.
* textures are an example of a resource that you might want to create
* here.
* <p>
* note that when the egl context is lost, all opengl resources associated
* with that context will be automatically deleted. you do not need to call
* the corresponding "gldelete" methods such as gldeletetextures to
* manually delete these lost resources.
* <p>
* @param gl the gl interface. use <code>instanceof</code> to
* test if the interface supports gl11 or higher interfaces.
* @param config the eglconfig of the created surface. can be used
* to create matching pbuffers.
*/
void onsurfacecreated(gl10 gl, eglconfig config);
/**
* called when the surface changed size.
* <p>
* called after the surface is created and whenever
* the opengl es surface size changes.
* <p>
* typically you will set your viewport here. if your camera
* is fixed then you could also set your projection matrix here:
* <pre class="prettyprint">
* void onsurfacechanged(gl10 gl, int width, int height) {
* gl.glviewport(0, 0, width, height);
* // for a fixed camera, set the projection too
* float ratio = (float) width / height;
* gl.glmatrixmode(gl10.gl_projection);
* gl.glloadidentity();
* gl.glfrustumf(-ratio, ratio, -1, 1, 1, 10);
* }
* </pre>
* @param gl the gl interface. use <code>instanceof</code> to
* test if the interface supports gl11 or higher interfaces.
* @param width
* @param height
*/
void onsurfacechanged(gl10 gl, int width, int height);
/**
* called to draw the current frame.
* <p>
* this method is responsible for drawing the current frame.
* <p>
* the implementation of this method typically looks like this:
* <pre class="prettyprint">
* void ondrawframe(gl10 gl) {
* gl.glclear(gl10.gl_color_buffer_bit | gl10.gl_depth_buffer_bit);
* //... other gl calls to render the scene ...
* }
* </pre>
* @param gl the gl interface. use <code>instanceof</code> to
* test if the interface supports gl11 or higher interfaces.
*/
void ondrawframe(gl10 gl);
}
void onsurfacecreated(gl10 gl, eglconfig config)
在surface创建或重建的情况下回调
void onsurfacechanged(gl10 gl, int width, int height)
在surface的大小发生变化的情况下回调
void ondrawframe(gl10 gl)
在这里实现绘制操作。当我们设置的rendermode为rendermode_continuously时，该函数将不断地执行；
当我们设置的rendermode为rendermode_when_dirty时，将只在创建完成和调用requestrender后才执行。一般我们选择rendermode_when_dirty渲染模式，避免过度绘制。
一般情况下，我们会自己实现一个renderer，然后为glsurfaceview设置renderer，可以说，renderer的编写是整个流程的核心步骤。以下是在void onsurfacecreated(gl10 gl, eglconfig config)进行的初始化操作和在void ondrawframe(gl10 gl)进行的绘制操作的流程图：
渲染yuv数据的renderer
2. 具体实现
坐标系介绍
android view坐标系
opengl世界坐标系
如图所示，和android的view坐标系不同，opengl的坐标系是笛卡尔坐标系。
android view的坐标系以左上角为原点，向右x递增，向下y递增；
而opengl坐标系以中心为原点，向右x递增，向上y递增。
着色器编写
/**
* 顶点着色器
*/
private static string vertex_shader =
" attribute vec4 attr_position;\n" +
" attribute vec2 attr_tc;\n" +
" varying vec2 tc;\n" +
" void main() {\n" +
" gl_position = attr_position;\n" +
" tc = attr_tc;\n" +
" }";
/**
* 片段着色器
*/
private static string frag_shader =
" varying vec2 tc;\n" +
" uniform sampler2d ysampler;\n" +
" uniform sampler2d usampler;\n" +
" uniform sampler2d vsampler;\n" +
" const mat3 convertmat = mat3( 1.0, 1.0, 1.0, -0.001, -0.3441, 1.772, 1.402, -0.7141, -0.58060);\n" +
" void main()\n" +
" {\n" +
" vec3 yuv;\n" +
" yuv.x = texture2d(ysampler, tc).r;\n" +
" yuv.y = texture2d(usampler, tc).r - 0.5;\n" +
" yuv.z = texture2d(vsampler, tc).r - 0.5;\n" +
" gl_fragcolor = vec4(convertmat * yuv, 1.0);\n" +
" }";
内建变量解释
gl_position
vertex_shader代码里的gl_position代表绘制的空间坐标。由于我们是二维绘制，所以直接传入opengl二维坐标系的左下(-1,-1)、右下(1,-1)、左上(-1,1)、右上(1,1)，也就是{-1,-1,1,-1,-1,1,1,1}
gl_fragcolor
frag_shader代码里的gl_fragcolor代表单个片元的颜色
其他变量解释
ysampler、usampler、vsampler
分别代表y、u、v纹理采样器
convertmat
根据以下公式：
r = y + 1.402 (v - 128) g = y - 0.34414 (u - 128) - 0.71414 (v - 128) b = y + 1.772 (u - 128)
我们可得到一个yuv转rgb的矩阵
1.0, 1.0, 1.0, 0, -0.344, 1.77, 1.403, -0.714, 0
部分类型、函数的解释
vec3、vec4
分别代表三维向量、四维向量。
vec4 texture2d(sampler2d sampler, vec2 coord)
以指定的矩阵将采样器的图像纹理转换为颜色值；如：
texture2d(ysampler, tc).r获取到的是y数据，
texture2d(usampler, tc).r获取到的是u数据，
texture2d(vsampler, tc).r获取到的是v数据。
在java代码中进行初始化
根据图像宽高创建y、u、v对应的bytebuffer纹理数据；
根据是否镜像显示、旋转角度选择对应的转换矩阵；
public void init(boolean ismirror, int rotatedegree, int framewidth, int frameheight) {
if (this.framewidth == framewidth
&& this.frameheight == frameheight
&& this.rotatedegree == rotatedegree
&& this.ismirror == ismirror) {
return;
}
datainput = false;
this.framewidth = framewidth;
this.frameheight = frameheight;
this.rotatedegree = rotatedegree;
this.ismirror = ismirror;
yarray = new byte[this.framewidth * this.frameheight];
uarray = new byte[this.framewidth * this.frameheight / 4];
varray = new byte[this.framewidth * this.frameheight / 4];
int yframesize = this.frameheight * this.framewidth;
int uvframesize = yframesize >> 2;
ybuf = bytebuffer.allocatedirect(yframesize);
ybuf.order(byteorder.nativeorder()).position(0);
ubuf = bytebuffer.allocatedirect(uvframesize);
ubuf.order(byteorder.nativeorder()).position(0);
vbuf = bytebuffer.allocatedirect(uvframesize);
vbuf.order(byteorder.nativeorder()).position(0);
// 顶点坐标
squarevertices = bytebuffer
.allocatedirect(glutil.square_vertices.length * float_size_bytes)
.order(byteorder.nativeorder())
.asfloatbuffer();
squarevertices.put(glutil.square_vertices).position(0);
//纹理坐标
if (ismirror) {
switch (rotatedegree) {
case 0:
coordvertice = glutil.mirror_coord_vertices;
break;
case 90:
coordvertice = glutil.rotate_90_mirror_coord_vertices;
break;
case 180:
coordvertice = glutil.rotate_180_mirror_coord_vertices;
break;
case 270:
coordvertice = glutil.rotate_270_mirror_coord_vertices;
break;
default:
break;
}
} else {
switch (rotatedegree) {
case 0:
coordvertice = glutil.coord_vertices;
break;
case 90:
coordvertice = glutil.rotate_90_coord_vertices;
break;
case 180:
coordvertice = glutil.rotate_180_coord_vertices;
break;
case 270:
coordvertice = glutil.rotate_270_coord_vertices;
break;
default:
break;
}
}
coordvertices = bytebuffer.allocatedirect(coordvertice.length * float_size_bytes).order(byteorder.nativeorder()).asfloatbuffer();
coordvertices.put(coordvertice).position(0);
}
在surface创建完成时进行renderer初始化
private void initrenderer() {
rendererready = false;
createglprogram();
//启用纹理
gles20.glenable(gles20.gl_texture_2d);
//创建纹理
createtexture(framewidth, frameheight, gles20.gl_luminance, ytexture);
createtexture(framewidth / 2, frameheight / 2, gles20.gl_luminance, utexture);
createtexture(framewidth / 2, frameheight / 2, gles20.gl_luminance, vtexture);
rendererready = true;
}
其中createglprogram用于创建opengl program并关联着色器代码中的变量
private void createglprogram() {
int programhandlemain = glutil.createshaderprogram();
if (programhandlemain != -1) {
// 使用着色器程序
gles20.gluseprogram(programhandlemain);
// 获取顶点着色器变量
int glposition = gles20.glgetattriblocation(programhandlemain, "attr_position");
int texturecoord = gles20.glgetattriblocation(programhandlemain, "attr_tc");
// 获取片段着色器变量
int ysampler = gles20.glgetuniformlocation(programhandlemain, "ysampler");
int usampler = gles20.glgetuniformlocation(programhandlemain, "usampler");
int vsampler = gles20.glgetuniformlocation(programhandlemain, "vsampler");
//给变量赋值
/**
* gles20.gl_texture0 和 ysampler 绑定
* gles20.gl_texture1 和 usampler 绑定
* gles20.gl_texture2 和 vsampler 绑定
*
* 也就是说 gluniform1i的第二个参数代表图层序号
*/
gles20.gluniform1i(ysampler, 0);
gles20.gluniform1i(usampler, 1);
gles20.gluniform1i(vsampler, 2);
gles20.glenablevertexattribarray(glposition);
gles20.glenablevertexattribarray(texturecoord);
/**
* 设置vertex shader数据
*/
squarevertices.position(0);
gles20.glvertexattribpointer(glposition, glutil.count_per_square_vertice, gles20.gl_float, false, 8, squarevertices);
coordvertices.position(0);
gles20.glvertexattribpointer(texturecoord, glutil.count_per_coord_vertices, gles20.gl_float, false, 8, coordvertices);
}
}
其中createtexture用于根据宽高和格式创建纹理
private void createtexture(int width, int height, int format, int[] textureid) {
//创建纹理
gles20.glgentextures(1, textureid, 0);
//绑定纹理
gles20.glbindtexture(gles20.gl_texture_2d, textureid[0]);
/**
* {@link gles20#gl_texture_wrap_s}代表左右方向的纹理环绕模式
* {@link gles20#gl_texture_wrap_t}代表上下方向的纹理环绕模式
*
* {@link gles20#gl_repeat}：重复
* {@link gles20#gl_mirrored_repeat}：镜像重复
* {@link gles20#gl_clamp_to_edge}：忽略边框截取
*
* 例如我们使用{@link gles20#gl_repeat}：
*
* squarevertices coordvertices
* -1.0f, -1.0f, 1.0f, 1.0f,
* 1.0f, -1.0f, 1.0f, 0.0f, -> 和textureview预览相同
* -1.0f, 1.0f, 0.0f, 1.0f,
* 1.0f, 1.0f 0.0f, 0.0f
*
* squarevertices coordvertices
* -1.0f, -1.0f, 2.0f, 2.0f,
* 1.0f, -1.0f, 2.0f, 0.0f, -> 和textureview预览相比，分割成了4 块相同的预览（左下，右下，左上，右上）
* -1.0f, 1.0f, 0.0f, 2.0f,
* 1.0f, 1.0f 0.0f, 0.0f
*/
gles20.gltexparameteri(gles20.gl_texture_2d, gles20.gl_texture_wrap_s, gles20.gl_repeat);
gles20.gltexparameteri(gles20.gl_texture_2d, gles20.gl_texture_wrap_t, gles20.gl_repeat);
/**
* {@link gles20#gl_texture_min_filter}代表所显示的纹理比加载进来的纹理小时的情况
* {@link gles20#gl_texture_mag_filter}代表所显示的纹理比加载进来的纹理大时的情况
*
* {@link gles20#gl_nearest}：使用纹理中坐标最接近的一个像素的颜色作为需要绘制的像素颜色
* {@link gles20#gl_linear}：使用纹理中坐标最接近的若干个颜色，通过加权平均算法得到需要绘制的像素颜色
*/
gles20.gltexparameteri(gles20.gl_texture_2d, gles20.gl_texture_min_filter, gles20.gl_nearest);
gles20.gltexparameteri(gles20.gl_texture_2d, gles20.gl_texture_mag_filter, gles20.gl_linear);
gles20.glteximage2d(gles20.gl_texture_2d, 0, format, width, height, 0, format, gles20.gl_unsigned_byte, null);
}
在java代码中调用绘制
在数据源获取到时裁剪并传入帧数据
@override
public void onpreview(final byte[] nv21, camera camera) {
//裁剪指定的图像区域
imageutil.cropnv21(nv21, this.squarenv21, previewsize.width, previewsize.height, croprect);
//刷新glsurfaceview
roundcameraglsurfaceview.refreshframenv21(this.squarenv21);
}
nv21数据裁剪代码
/**
* 裁剪nv21数据
*
* @param originnv21 原始的nv21数据
* @param cropnv21 裁剪结果nv21数据，需要预先分配内存
* @param width 原始数据的宽度
* @param height 原始数据的高度
* @param left 原始数据被裁剪的区域的左边界
* @param top 原始数据被裁剪的区域的上边界
* @param right 原始数据被裁剪的区域的右边界
* @param bottom 原始数据被裁剪的区域的下边界
*/
public static void cropnv21(byte[] originnv21, byte[] cropnv21, int width, int height, int left, int top, int right, int bottom) {
int halfwidth = width / 2;
int cropimagewidth = right - left;
int cropimageheight = bottom - top;
//原数据y左上
int originalylinestart = top * width;
int targetyindex = 0;
//原数据uv左上
int originaluvlinestart = width * height + top * halfwidth;
//目标数据的uv起始值
int targetuvindex = cropimagewidth * cropimageheight;
for (int i = top; i < bottom; i++) {
system.arraycopy(originnv21, originalylinestart + left, cropnv21, targetyindex, cropimagewidth);
originalylinestart += width;
targetyindex += cropimagewidth;
if ((i & 1) == 0) {
system.arraycopy(originnv21, originaluvlinestart + left, cropnv21, targetuvindex, cropimagewidth);
originaluvlinestart += width;
targetuvindex += cropimagewidth;
}
}
}
传给glsurafceview并刷新帧数据
/**
* 传入nv21刷新帧
*
* @param data nv21数据
*/
public void refreshframenv21(byte[] data) {
if (rendererready) {
ybuf.clear();
ubuf.clear();
vbuf.clear();
putnv21(data, framewidth, frameheight);
datainput = true;
requestrender();
}
}
其中putnv21用于将nv21中的y、u、v数据分别取出
/**
* 将nv21数据的y、u、v分量取出
*
* @param src nv21帧数据
* @param width 宽度
* @param height 高度
*/
private void putnv21(byte[] src, int width, int height) {
int ysize = width * height;
int framesize = ysize * 3 / 2;
//取分量y值
system.arraycopy(src, 0, yarray, 0, ysize);
int k = 0;
//取分量uv值
int index = ysize;
while (index < framesize) {
varray[k] = src[index++];
uarray[k++] = src[index++];
}
ybuf.put(yarray).position(0);
ubuf.put(uarray).position(0);
vbuf.put(varray).position(0);
}
在执行requestrender后，ondrawframe函数将被回调，在其中进行三个纹理的数据绑定并绘制
@override
public void ondrawframe(gl10 gl) {
// 分别对每个纹理做激活、绑定、设置数据操作
if (datainput) {
//y
gles20.glactivetexture(gles20.gl_texture0);
gles20.glbindtexture(gles20.gl_texture_2d, ytexture[0]);
gles20.gltexsubimage2d(gles20.gl_texture_2d,
0,
0,
0,
framewidth,
frameheight,
gles20.gl_luminance,
gles20.gl_unsigned_byte,
ybuf);
//u
gles20.glactivetexture(gles20.gl_texture1);
gles20.glbindtexture(gles20.gl_texture_2d, utexture[0]);
gles20.gltexsubimage2d(gles20.gl_texture_2d,
0,
0,
0,
framewidth >> 1,
frameheight >> 1,
gles20.gl_luminance,
gles20.gl_unsigned_byte,
ubuf);
//v
gles20.glactivetexture(gles20.gl_texture2);
gles20.glbindtexture(gles20.gl_texture_2d, vtexture[0]);
gles20.gltexsubimage2d(gles20.gl_texture_2d,
0,
0,
0,
framewidth >> 1,
frameheight >> 1,
gles20.gl_luminance,
gles20.gl_unsigned_byte,
vbuf);
//在数据绑定完成后进行绘制
gles20.gldrawarrays(gles20.gl_triangle_strip, 0, 4);
}
}
即可完成绘制。
四、加一层边框
有时候需求并不仅仅是圆形预览这么简单，我们可能还要为相机预览加一层边框
边框效果
一样的思路，我们动态地修改边框值，并进行重绘。
边框自定义view中的相关代码如下：
@override
protected void ondraw(canvas canvas) {
super.ondraw(canvas);
if (paint == null) {
paint = new paint();
paint.setstyle(paint.style.stroke);
paint.setantialias(true);
sweepgradient sweepgradient = new sweepgradient(((float) getwidth() / 2), ((float) getheight() / 2),
new int[]{color.green, color.cyan, color.blue, color.cyan, color.green}, null);
paint.setshader(sweepgradient);
}
drawborder(canvas, 6);
}
private void drawborder(canvas canvas, int rectthickness) {
if (canvas == null) {
return;
}
paint.setstrokewidth(rectthickness);
path drawpath = new path();
drawpath.addroundrect(new rectf(0, 0, getwidth(), getheight()), radius, radius, path.direction.cw);
canvas.drawpath(drawpath, paint);
}
public void turnround() {
invalidate();
}
public void setradius(int radius) {
this.radius = radius;
}
五、完整demo代码：
https://github.com/wangshengyang1996/glcamerademo
使用camera api和camera2 api并选择最接近正方形的预览尺寸
使用camera api并为其动态添加一层父控件，达到正方形预览的效果
使用camera api获取预览数据，使用opengl的方式进行显示最后，给大家推荐一个好用的android免费离线人脸识别的sdk，可以和本文实现技术的完美结合：
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