给android增加屏幕校准

android原始版本里是没有屏幕校准功能的，tp坐标到lcd坐标是完全按照线性关系来转换的。例如，tp坐标是(X_t ,Y_t )分辨率是（W_t x H_t ），lcd坐标是(X,Y)，分辨率是(W x H)，则 X=(X_t *W)/W_t， Y=(Y_t *H)/H_t 。但是一般触摸屏不是完全线性的，自然转换关系也就不一样了，好在有tslib，能帮我们解决这个问题。但是android里没有tslib，我们也不需要完全将tslib移植过来，只需要其中根据采样点生成转换矩阵的部分，这部分是由ts_calibrate.c文件中的perform_calibration()函数来实现的。所以只需要将该函数移植过来就可以。这里将该函数及用到的数据结构代码贴出来如下：

typedef struct{ int x[5], xfb[5];//x[5],y[5]是分别是tp五个点的x,y坐标，xfb[5],yfb[5]是lcd五个点的x,y坐标。 int y[5], yfb[5]; int a[7];//a[7]是生成的7个转换参数，tp到lcd坐标转换方程是： xfb = (x*a[1]+y*a[2]+a[0])/a[6] }calibration; // yfb = (x*a[4]+y*a[5]+a[3])/a[6] int perform_calibration(calibration *cal) { int j; float n, x, y, x2, y2, xy, z, zx, zy; float det, a, b, c, e, f, i; float scaling = 65536.0; // Get sums for matrix n = x = y = x2 = y2 = xy = 0; for(j=0;j<5;j++) { n += 1.0; x += (float)cal->x[j]; y += (float)cal->y[j]; x2 += (float)(cal->x[j]*cal->x[j]); y2 += (float)(cal->y[j]*cal->y[j]); xy += (float)(cal->x[j]*cal->y[j]); } // Get determinant of matrix -- check if determinant is too small det = n*(x2*y2 - xy*xy) + x*(xy*y - x*y2) + y*(x*xy - y*x2); if(det < 0.1 && det > -0.1) { printf("ts_calibrate: determinant is too small -- %f/n",det); return 0; } // Get elements of inverse matrix a = (x2*y2 - xy*xy)/det; b = (xy*y - x*y2)/det; c = (x*xy - y*x2)/det; e = (n*y2 - y*y)/det; f = (x*y - n*xy)/det; i = (n*x2 - x*x)/det; // Get sums for x calibration z = zx = zy = 0; for(j=0;j<5;j++) { z += (float)cal->xfb[j]; zx += (float)(cal->xfb[j]*cal->x[j]); zy += (float)(cal->xfb[j]*cal->y[j]); } // Now multiply out to get the calibration for framebuffer x coord cal->a[0] = (int)((a*z + b*zx + c*zy)*(scaling)); cal->a[1] = (int)((b*z + e*zx + f*zy)*(scaling)); cal->a[2] = (int)((c*z + f*zx + i*zy)*(scaling)); printf("%f %f %f/n",(a*z + b*zx + c*zy), (b*z + e*zx + f*zy), (c*z + f*zx + i*zy)); // Get sums for y calibration z = zx = zy = 0; for(j=0;j<5;j++) { z += (float)cal->yfb[j]; zx += (float)(cal->yfb[j]*cal->x[j]); zy += (float)(cal->yfb[j]*cal->y[j]); } // Now multiply out to get the calibration for framebuffer y coord cal->a[3] = (int)((a*z + b*zx + c*zy)*(scaling)); cal->a[4] = (int)((b*z + e*zx + f*zy)*(scaling)); cal->a[5] = (int)((c*z + f*zx + i*zy)*(scaling)); printf("%f %f %f/n",(a*z + b*zx + c*zy), (b*z + e*zx + f*zy), (c*z + f*zx + i*zy)); // If we got here, we're OK, so assign scaling to a[6] and return cal->a[6] = (int)scaling; return 1; ｝

 

有了上面的基础，接下来就是将上面的代码移植到android中并在setting里面添加屏幕校准入口，要完成这些，需要修改的文件有：

1. frameworks/base/services/java/com/android/server/InputDevice.java

2. packages/apps/Settings/AndroidManifest.xml

3. packages/apps/Settings/res/xml/settings.xml

另外在Setting源码目录里再添加一个Calibration.java文件。

 

frameworks/base/services/java/com/android/server/InputDevice.java修改的地方如下（红色 表示添加，蓝色 表示删除）：

public class InputDevice {
     static final boolean DEBUG_POINTERS = false;
     static final boolean DEBUG_HACKS = false;
 
     /** Amount that trackball needs to move in order to generate a key event. */
     static final int TRACKBALL_MOVEMENT_THRESHOLD = 6;
 
     /** Maximum number of pointers we will track and report. */
     static final int MAX_POINTERS = 10;
 
     static final String CALIBRATION_FILE="/data/pointercal";
 
     final int id;
     final int classes;
     final String name;
     final AbsoluteInfo absX;
     final AbsoluteInfo absY;
     final AbsoluteInfo absPressure;
     final AbsoluteInfo absSize;

 

     ....................

 

            final AbsoluteInfo absX = device.absX;
             final AbsoluteInfo absY = device.absY;
             final AbsoluteInfo absPressure = device.absPressure;
             final AbsoluteInfo absSize = device.absSize;
 
             float tmpX = 0;   
             float tmpY = 0;
             String prop = SystemProperties.get("sys.config.calibrate", "noset");
 
             if ( !prop.equalsIgnoreCase("loaded") )
             {
                     if ( prop.equalsIgnoreCase("start") )
                     {
                         TransformInfo.xs =  0;
                         TransformInfo.ys =  0;
                     }
                     else if ( prop.equalsIgnoreCase("done") )
               &nbs