I'm making use of a custom layout with a custom view. The layout is a RelativeLayout and the view is an ImageView.
The ImageView is scaled based on the smallest width or height of the screen, to keep the ratio of the image I want to display while still showing the entire image.
What I can't figure out is how to center align the ImageView in the layout.
It's a very basic layout:
public class ImageViewLayout extends RelativeLayout {
public final CustomImageView mCustomImageView;
public ImageViewLayout(Context context) {
super(context);
mCustomImageView = new CustomImageView(context);
this.addView(mCustomImageView);
}
}
And the ImageView is (very large but I'll try and keep it down for readability and extend if wanted):
public class CustomImageView extends ImageView implements GestureDetector.OnGestureListener {
public CustomImageView(Context context) {
super(context);
mContext = context;
init();
}
public init() {
setBackgroundColor(0xFF222222);
LayoutParams params = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);
setLayoutParams(params);
calculateAndDisplayBitmap();
}
}
I calculate the size of the image I want to display after the initial layout and the image is always placed top left, no matter what kind of tricks I try to do with the layout.
The background is stretched to fill the entire screen (FILL_PARENT in the parameters suggest that it should) but no matter what I do to the layout I can't get the bitmap to center.
I'm really opting for a layout-based positioning of the bitmap instead of a calculated-pixel-based one.
Add this line in ImageViewLayout.java
mCustomImageView.setGravity(Gravity.CENTER);
Related
I'm making a custom View thats derived from an ImageViewand I control where the image has to be within this ImageView using padding.
I have set OnClickListener on my custom ImageView that resizes it:
image.setOnClickListener(new ImageView.OnClickListener(){
#Override
public void onClick(View v) {
image.resize_image();
}
});
and this is how this function is looking like
public void resize_image(){
ViewGroup.LayoutParams params = getLayoutParams();
params.height = new_heigth;
params.width = new_width;
setLayoutParams(params);
}
After this resizing is done I don't want my displayed image to change size (only the custom ImageView is changing size so I can draw an extra stuff around this image) within my custom ImageView so inside onDraw(Canvas) member function I set the new padding
class custom_ImageView extends ImageView{
//...
#Override
protected void onDraw(Canvas canvas) {
//...
setPadding(new_left_padding, new_top_padding, new_right_padding, new_bottom_padding);
//...
}
//...
}
Result is that width and heigth are changed like I wanted but my displayed image is neither in the right position or size.
Interesting this is that if I add an extra line of invalidate(); in the end of my resize_image() and I click on my custom_ImageView twice - on the 2nd click image draws itself in right size and position like I wanted.
Can anyone tell me why this is happening?
I kind of worked around this by not using ImageView at all but just drawing image where it needs to be by using Canvas.drawBitmap(Bitmap, RectF, RectF, Paint)
This way I don't have to specify images location using setPadding within onDraw, but I can do it simply by specifying position using RectF.
New Android programmer here.
I'm trying to display an .png image as a bitmap on Android. The only way I have been able to display the converted image at all is with a custom class that extends View. However, my image is too large to be displayed entirely on the screen and I would like to be able to scroll with it. But when I define a ScrollView and put the Canvas with the Bitmap into it, I get a blank screen. I had no luck setting this up with the layout file, so it is all done in the Activity class.
This is where the Activity is created:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ScrollView scroll = new ScrollView(this);
scroll.addView(new CustomView(this));
setContentView(scroll);
}
And this is my CustomView class:
private class CustomView extends View{
public CustomView(Context context) {
super(context);
}
#Override
protected void onDraw(Canvas canvas){
Bitmap bitmapMap = BitmapFactory.decodeResource(getResources(),R.drawable.resourceimage);
canvas.drawBitmap(bitmapMap,0,0,null);
this.setWillNotDraw(false);
}
}
And if I replace this line of code in my Activity: setContentView(scroll)
with this line: setContentView(new CustomView(this)), I can see the image, albeit not the entire image. So, is there a way to set this up in the layout files instead? Or is there something I'm missing that I need to declare in the ScrollView class?
EDIT: I would prefer not to use ImageView, because I would like to change the image in specific locations, and using bitmap seemed to be the easiest way to accomplish that, via x and y coordinates.
Your custom view needs to override the onMeasure method and properly set the measured width and height so that the parent views (in this case the ScrollView) can know how much space to allocate for the child.
I'm using android 2.0. I have a view (just a sipmle linearlayout with an image as background), which contains 3 imagebuttons. When I touch any part of this view, my buttons are not touchable any more. As they are disabled! How can I disable the touchability of the background? I just want to be able to touch the buttons even if I put my finger on the other parts of the view. Is that possible?
The code sample:
public class myView extends LinearView {
public myView(Context context) {
super(context);
}
public setView(Context context) {
setBackgroundDrawable(backImg);
setOrientation(LinearLayout.HORIZONTAL);
setGravity(Gravity.CENTER);
setScrollContainer(false);
ImageButton imgBtn0 = new ImageButton(context);
imgBtn0.setBackgroundColor(Color.TRANSPARENT);
imgBtn0.setBackgroundDrawable(imgBtnD0);
imgBtn0.setDrawingCacheEnabled(true);
imgBtn0.setOnTouchListener(new TouchListener(context, id0));
...
addView(imgBtn0, 0);
addView(imgBtn1, 1);
addView(imgBtn2, 2);
}
}
you can disable the touch of the linearlayout using android:clicable="false" but how will you figure out which image button to be clicked if the user clicks in the background?
Layouting in Android is getting me rather perplexed.
I'm slowly implementing a custom ImageView where I'd like to make use of the ZoomButtonsController.
However, I would like to decide where the zoom buttons go in the layout and I can't figure out how to move them from the default bottom center position.
I have been experimenting with layouting simple views such as buttons in the main activity and this seems to be working as I would guess and expect.
In the case of the ZoomButtonsController I would however like to reposition them. I'm using a RelativeLayout as the mail layout and add the ZoomButtonsController within the custom ImageView.
The Activity code
public class ImageViewActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
CustomImageView imageView = new CustomImageView(this);
relativeLayout.addView(imageView);
}
}
The CustomImageView code
public class CustomImageView extends ImageView {
private ZoomButtonsController mZoomButtons;
public CustomImageView(Context context) {
super(context);
RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.FILL_PARENT, RelativeLayout.LayoutParams.FILL_PARENT);
mZoomButtons = new ZoomButtonsController(this);
mZoomButtons.getZoomControls();
layoutParams.addRule(RelativeLayout.ALIGN_PARENT_TOP);
layoutParams.addRule(RelativeLayout.CENTER_HORIZONTAL);
setLayoutParams(layoutParams);
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
Log.d("TAG", "touch");
mZoomButtons.setVisible(true);
return true;
}
}
I've tested with WRAP_CONTENT in the parameters, but this only makes the zoom buttons disappear.
As a matter of fact, I couldn't position the ZoomButtonsController in any way and in the end had to accept the default placement.
I am very new to Android and I am having problems figuring out how to layout views within a RelativeLayout programmatically. What I want to do is create 4 circles (child views) with a certain radius (say 50px) in the center of the RelativeLayout container, so it would look like I have an imaginary square in the center of the RelativeLayout and each vertex is the center for one of the circles.
I am able to draw the circle in the view; that is simple enough :)
class CircleView extends View {
...
protected void onDraw(Canvas canvas) {
// draw circle on canvas
}
}
What I cannot figure out is how to layout the views. It seems to draw them on top of each other, even though I am setting LayoutParams and an Id for each of the child views.
class Circles extends RelativeLayout {
public Circles(Context c) {
super(c);
addChildViews();
}
...
private void addChildViews() {
final Context c = getContext();
final CircleView v0 = new CircleView(c);
v0.setId(0);
final RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.LEFT_OF, 1);
params.addRule(RelativeLayout.ABOVE, 2);
v0.setLayoutParams(params);
addView(v0);
....
// and so on, with relative layout params for other 3 views
}
}
Can somebody put me on the right track please? I also don't know if I am not calling addChildViews at the right time in the drawing cycle, and if this is what is leading to them being drawn on top of each other. Many thanks for any help.
Two things
1)The default action of a View is to fill its parent, so by applying (LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT) as your LayoutParams, you're creating four views with heights and widths the size of your parent layout (presumably the screen), so you'd only see one as the others would be positioned offscreen.
To fix this, either set the size you want the circles to be as your LayoutParms,
float dpi = getResources().getDisplayMetrics().density;
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams((int)(50.0f * dpi), (int)(50.0f * dpi));
or you could override the onMeasure(int x, int y) method in your Circle View like so
#Override
public void onMeasure(int x, int y) {
float dpi = getResources().getDisplayMetrics().density;
setMeasuredDimension((int)(50.0f * dpi), (int)(50.0f * dpi));
}
2) Don't set your View id to 0...I can't remember if it's system reserved or what, but it doesn't play nice.
Additionally, if you want all the circles centered in your Circles, you'll want to set its gravity to center like so.
public class Circles extends RelativeLayout {
public Circles (Context ctx) {
super(ctx);
this.setGravity(Gravity.CENTER);
addViewChildren();
}
This will center all of the Circles children, giving you the desired result.