Pixel to density independent pixel to pixel conversion
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Physical pixel (px)
Density independent pixel (dp)
Dots per inch (dpi) .. physical pixels per inch
px = dp * (dpi / 160)
Density independent pixel (dp)
Dots per inch (dpi) .. physical pixels per inch
px = dp * (dpi / 160)
public static int dpToPx(int dp)
{
return (int) (dp * Resources.getSystem().getDisplayMetrics().density);
}
public static int pxToDp(int px)
{
return (int) (px / Resources.getSystem().getDisplayMetrics().density);
}
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Další témata ....(Topics)
StringBuilder, res/raw folder, try catch finaly throws, BufferedReader, InputStream, openRawResource, getResources Android example
MainActivity.java
MainActivity.java
public class MainActivity extends Activity {
TextView txtV;
Context cntx;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
txtV = (TextView)findViewById(R.id.idLabel);
cntx = this;
try {
StringBuilder strBuilder = myFunction(cntx);
txtV.setText(strBuilder);
} catch (IOException e) {
e.printStackTrace();
}
}
private StringBuilder myFunction(Context context) throws IOException {
final Resources resources = context.getResources();
InputStream inputStream = resources.openRawResource(R.raw.my_file);
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
StringBuilder strBuild = new StringBuilder();
try {
String line;
while ((line = reader.readLine()) != null) {
strBuild.append(line);
}
} finally {
reader.close();
}
return strBuild;
}
}
"id cannot be resolved or is not a field” error
If you copy project to workspace or some code from other project you can get this error.
Try remove or add import your R file:
Check xml files.
Clean project by menu Project-Clean
Maybe you have to create new project end copy old source files to new project folders.
If you copy project to workspace or some code from other project you can get this error.
Try remove or add import your R file:
import com.example.app.R
Check xml files.
Clean project by menu Project-Clean
Maybe you have to create new project end copy old source files to new project folders.
Codec, compress(), CompressFormat, quality, decodeByteArray(), Android example source code with image.

public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
private static Bitmap codec(Bitmap src, Bitmap.CompressFormat format,
int quality) {
ByteArrayOutputStream os = new ByteArrayOutputStream();
src.compress(format, quality, os);
byte[] array = os.toByteArray();
return BitmapFactory.decodeByteArray(array, 0, array.length);
}
private static class SampleView extends View {
// CONSTRUCTOR
public SampleView(Context context) {
super(context);
setFocusable(true);
}
@Override
protected void onDraw(Canvas canvas) {
Paint paint = new Paint();
canvas.drawColor(Color.GRAY);
// you need to insert some image flower_blue into res/drawable folder
Bitmap b = BitmapFactory.decodeResource(getResources(), R.drawable.flower_blue);
// Best of quality is 80 and more, 3 is very low quality of image
Bitmap bJPGcompress = codec(b, Bitmap.CompressFormat.JPEG, 3);
// get dimension of bitmap getHeight() getWidth()
int h = b.getHeight();
canvas.drawBitmap(b, 10,10, paint);
canvas.drawBitmap(bJPGcompress, 10,10 + h + 10, paint);
}
}
}

Context context = getApplicationContext();
Drawable drawable = context.getResources().getDrawable(R.drawable.my_image);
// convert drawable to bitmap
Bitmap bitmap = ((BitmapDrawable)drawable).getBitmap();
// convert bitmap to drawable
Drawable d = new BitmapDrawable(bitmap);
Android example source code.
Cross Button in EditText Android for deleting clearing text in EditText Example source code:
Example allow delete text in EditText by cross button, or do Button click performance.
main.xml type your package name and class
Put into drawable folder cross and ok image.
CustomEditText.java
YourActivity.java
//android.okhelp.cz/wiktionary-aplikace-pro-android/
Example allow delete text in EditText by cross button, or do Button click performance.
main.xml type your package name and class
Put into drawable folder cross and ok image.
<cz.okhelp.wiktionary.CustomEditText
android:id="@+id/editTextZadejSlovo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="2"
android:ems="10"
android:hint="TypeAndPressGreen"
android:singleLine="true"
android:lines="1"
android:maxLines="1"
android:drawableLeft="@drawable/cross"
android:drawableRight="@drawable/ok" />
<!--button is invisible 0 height 0 width for performance click on button in EditText-->
<Button
android:id="@+id/btnGO"
android:layout_width="0sp"
android:layout_height="0sp"
android:layout_weight="0"
android:text="GO" />
CustomEditText.java
package cz.okhelp.wiktionary; // your package name
import android.content.Context;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.widget.Button;
import android.widget.EditText;
public class CustomEditText extends EditText
{
private Drawable dLeft,dRight;
private Rect lBounds,rBounds;
private static Button btnOk;
public CustomEditText(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public CustomEditText(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomEditText(Context context) {
super(context);
}
@Override
public void setCompoundDrawables(Drawable left, Drawable top,
Drawable right, Drawable bottom)
{
if(left !=null) {
dLeft = left;
}
if(right !=null){
dRight = right;
}
super.setCompoundDrawables(left, top, right, bottom);
}
@Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_ENTER) {
btnOk.requestFocus();
btnOk.performClick();
}
return super.onKeyUp(keyCode, event);
}
@Override
public boolean onTouchEvent(MotionEvent event)
{
final int x = (int)event.getX();
final int y = (int)event.getY();
if(event.getAction() == MotionEvent.ACTION_UP && dLeft!=null) {
lBounds = dLeft.getBounds();
int n1 = this.getLeft();
int n2 = this.getLeft()+lBounds.width();
int n3 = this.getPaddingTop();
int n4 = this.getHeight()-this.getPaddingBottom();
// leva strana
if( x>=(this.getLeft())
&& x<=(this.getLeft()+lBounds.width())
&& y>=this.getPaddingTop()
&& y<=(this.getHeight()-this.getPaddingBottom()))
{
this.setText("");
event.setAction(MotionEvent.ACTION_CANCEL);//use this to prevent the keyboard from coming up
}
}
if(event.getAction() == MotionEvent.ACTION_UP && dRight!=null)
{
rBounds = dRight.getBounds();
int n1 = this.getRight()-rBounds.width();
int n2 = this.getRight()-this.getPaddingRight();
int n3 = this.getPaddingTop();
int n4 = this.getHeight()-this.getPaddingBottom();
// prava strana
if(x>=(this.getRight()-rBounds.width()) && x<=(this.getRight()-this.getPaddingRight())
&& y>=this.getPaddingTop() && y<=(this.getHeight()-this.getPaddingBottom()))
{
btnOk.requestFocus();
btnOk.performClick();
event.setAction(MotionEvent.ACTION_CANCEL);//use this to prevent the keyboard from coming up
}
}
return super.onTouchEvent(event);
}
@Override
protected void finalize() throws Throwable
{
dRight = null;
rBounds = null;
super.finalize();
}
public void setBtnOk(Button btnOk) {
this.btnOk = btnOk;
}
public Button getBtnOk() {
return btnOk;
}
}
YourActivity.java
//onCreate
Button mBtnGO = (Button)findViewById(R.id.btnGO);
CustomEditText mEditZadani = (CustomEditText)this.findViewById(R.id.editTextZadejSlovo);
mEditZadani.setBtnOk(mBtnGO);
mBtnGO.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// do stuff for signInButtonClick
}
});
//android.okhelp.cz/wiktionary-aplikace-pro-android/
Editace: 2015-12-02 19:01:06
Počet článků v kategorii: 396
Url:pixel-to-density-independent-pixel-to-pixel-conversion
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