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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： X

_lcd

= (X

_tp

*a[1] + Y

_tp

*a[2] + a[0])/a[6]

}calibration;               //  Y

_lcd

= (X

_tp

*a[4] + Y

_tp

*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”) )

{


readCalibrate();

}

if ( TransformInfo.xs == 0 && absX != null )

{


TransformInfo.x1 = w;

TransformInfo.y1 = 0;

TransformInfo.z1 = 0-absX.minValue*w;

TransformInfo.xs =  absX.range;

}

if ( TransformInfo.ys == 0 && absY != null )

{


TransformInfo.x2 = 0;

TransformInfo.y2 = h;

TransformInfo.z2 = 0-absY.minValue*h;

TransformInfo.ys =  absY.range;

}

SystemProperties.set(“sys.config.calibrate”, “loaded”);

}

for (int i=0; i<numPointers; i++) {


final int j = i * MotionEvent.NUM_SAMPLE_DATA;

tmpX = reportData[j + MotionEvent.SAMPLE_X];

tmpY = reportData[j + MotionEvent.SAMPLE_Y];

if (absX != null ) {


reportData[j + MotionEvent.SAMPLE_X] =

((reportData[j + MotionEvent.SAMPLE_X]-absX.minValue)

/ absX.range) * w;

reportData[j + MotionEvent.SAMPLE_X] = (TransformInfo.x1 * tmpX + TransformInfo.y1 * tmpY + TransformInfo.z1) / TransformInfo.xs;

}

if (absY != null ) {


reportData[j + MotionEvent.SAMPLE_Y] =

((reportData[j + MotionEvent.SAMPLE_Y]-absY.minValue)

/ absY.range) * h;

reportData[j + MotionEvent.SAMPLE_Y] = (TransformInfo.x2 * tmpX + TransformInfo.y2 * tmpY + TransformInfo.z2) / TransformInfo.ys;

}

if (absPressure != null) {


reportData[j + MotionEvent.SAMPLE_PRESSURE] =

((reportData[j + MotionEvent.SAMPLE_PRESSURE]-absPressure.minValue)

/ (float)absPressure.range);

}

if (absSize != null) {


reportData[j + MotionEvent.SAMPLE_SIZE] =

((reportData[j + MotionEvent.SAMPLE_SIZE]-absSize.minValue)

/ (float)absSize.range);

}

…………………………….

static class AbsoluteInfo {


int minValue;

int maxValue;

int range;

int flat;

int fuzz;

};

static class TransformInfo {


static int x1;

static int y1;

static int z1;

static int x2;

static int y2;

static int z2;

static int xs;

static int ys;

};

InputDevice(int _id, int _classes, String _name,

AbsoluteInfo _absX, AbsoluteInfo _absY,

AbsoluteInfo _absPressure, AbsoluteInfo _absSize) {


id = _id;

classes = _classes;

name = _name;

absX = _absX;

absY = _absY;

absPressure = _absPressure;

absSize = _absSize;

TransformInfo.xs =  0;

TransformInfo.ys =  0;

readCalibrate();

}

static void readCalibrate(){


try {


FileInputStream is = new FileInputStream(CALIBRATION_FILE);

byte[] mBuffer = new byte[64];

int len = is.read(mBuffer);

is.close();

if (len > 0) {


int i;

for (i = 0; i < len; i++) {


if (mBuffer[i] == ‘/n’ || mBuffer[i] == 0) {


break;

}

}

len = i;

}

StringTokenizer st = new StringTokenizer(new String(mBuffer, 0, len));

TransformInfo.x1 = Integer.parseInt(st.nextToken());

TransformInfo.y1 = Integer.parseInt(st.nextToken());

TransformInfo.z1 = Integer.parseInt(st.nextToken());

TransformInfo.x2 = Integer.parseInt(st.nextToken());

TransformInfo.y2 = Integer.parseInt(st.nextToken());

TransformInfo.z2 = Integer.parseInt(st.nextToken());

TransformInfo.xs = Integer.parseInt(st.nextToken());

TransformInfo.ys = TransformInfo.xs;

SystemProperties.set(“sys.config.calibrate”, “loaded”);

} catch (java.io.FileNotFoundException e) {


Log.i(“InputDevice”, “calibration file not found exception”);

} catch (java.io.IOException e) {


Log.i(“InputDevice”, “io exception”);

} catch (java.lang.NumberFormatException e) {


Log.i(“InputDevice”, “number format exception”);

}

}

};

packages/apps/Settings/AndroidManifest.xml文件修改地方如下:

<activity android:name=”.fuelgauge.PowerUsageDetail”

android:label=”@string/details_title”>

<intent-filter>

<action android:name=”android.intent.action.MAIN” />

<category android:name=”android.intent.category.DEFAULT” />

</intent-filter>

</activity>

<activity android:name=”Calibration”

android:label=”@string/screen_calibration_settings”>

<intent-filter>

<action android:name=”android.intent.action.MAIN” />

<category android:name=”android.intent.category.DEFAULT” />

</intent-filter>

</activity>

<receiver android:name=”.widget.SettingsAppWidgetProvider” android:label=”@string/gadget_title”>

<intent-filter>

<action android:name=”android.appwidget.action.APPWIDGET_UPDATE” />

packages/apps/Settings/res/xml/settings.xml文件修改地方如下:

<com.android.settings.IconPreferenceScreen

settings:icon=”@drawable/ic_settings_date_time”

android:title=”@string/date_and_time_settings_title”>

<intent

android:action=”android.intent.action.MAIN”

android:targetPackage=”com.android.settings”

android:targetClass=”com.android.settings.DateTimeSettings” />

</com.android.settings.IconPreferenceScreen>

<!– touchscreen Calibration –>

<com.android.settings.IconPreferenceScreen

settings:icon=”@drawable/ic_settings_privacy”

android:title=”@string/screen_calibration_settings”>

<intent

android:action=”android.intent.action.MAIN”

android:targetPackage=”com.android.settings”

android:targetClass=”com.android.settings.Calibration”/>

</com.android.settings.IconPreferenceScreen>

<!– About Device –>

<com.android.settings.IconPreferenceScreen

settings:icon=”@drawable/ic_settings_about”

android:title=”@string/about_settings”>

<intent

android:action=”android.intent.action.MAIN”

android:targetPackage=”com.android.settings”

android:targetClass=”com.android.settings.DeviceInfoSettings” />

</com.android.settings.IconPreferenceScreen>

Calibration.java文件代码如下

转自：

http://blog.csdn.net/king_sundi/archive/2011/01/19/6152865.aspx

http://blogold.chinaunix.net/u3/90973/showart_2162315.html

http://blog.csdn.net/cpuwolf/archive/2011/01/11/6130010.aspx

http://blog.csdn.net/dafeifly/archive/2009/10/13/4662498.aspx