I have an image in a .png format with the alpha channel and i wish it to be clickable. The click should be detected only if the real image is clicked (not the alpha background).
<TouchableHighlight onPress={this.imgClick}>
<Image
source={this.img1}
/>
</TouchableHighlight>
And i want to create a clickable circle of these elements
Thank you for helping and i wish you a Merry X-Mas !!
You can detect where on the image has been clicked and then you should have some metadata on the image to detect that it is in the non-alpha bounds.
imgClick = ({nativeEvent: {locationX, locationY}}) => {
if (ImageService.inBounds(image, locationX, locationY)) {
// do your event handling here
}
}
ImageService would be where your metadata and logic is stored for each image. You probably want a simple point in polygon algorithm.
https://en.wikipedia.org/wiki/Point_in_polygon
Related
I am doing react native project. In that, I have to show custom image like toggle button, In that, for OFF one image and ON another image I have to display, And in that, two components should have to display according to ON/OFF states.
I am new to this domain.
I have knowledge to set image touchable/Onpress, but, How to set custom image and act like toggle according to that components switch.
this.toggleAction() = () => {
//switching components for ON/OFF states
}
<TouchableHighlight >
<Image style={styles.imagestyle}
source={require('./ic_toggle_on.png')} />
onPress={() => this.toggleAction()}>
</TouchableHighlight>
Any suggestions?
You need to store the current state of Toggle button in a state variable:
this.state={
toggle:false
}
then you need to change the state in the onPress method of your TouchableOpacity.
After that you just need conditional rendering to show the different images
render(
<TouchableOpacity onPress={()=>this.setState({toggle:!this.state.toggle})}>
{
this.state.toggle==true?
<Image src={ YOUR TOGGLE ON SOURCE}/>
:
<Image src={ YOUR TOGGLE Off SOURCE}/>
}
)
I'm trying to use SkiaSharp in Xamarin.forms to draw some polygons on top of an image.
The image is downloaded from a server and than cached in background. So I would prefer not to manipulate the image itself and instead draw a new canvas and place it in a new view on top of the image, like in the screenshots. (using relative layout)
As you can also see in the screenshots, placing the rectangular is not the problem but the "transparent" part is not really transparent.
Code of the first screenshot:
using (var paint = new SKPaint ()) {
paint.IsAntialias = true;
using (var path = new SKPath ()) {
path.MoveTo (0f, 0f);
path.LineTo (width, height);
path.LineTo (0, width);
path.Close ();
paint.Color = SKColors.Orange;
canvas.DrawPath (path, paint);
}
}
In the second I tried to use
canvas.Clear(SKColors.Transparent);
but it only changes to the black background.
Does anyone know whether it is possible to have completely transparent parts in a skia view?
Your question helped me solve this today:
As well as setting the canvas' colour as transparent, the containing Xamarin Forms element needs to be transparent too!
C#
canvas.Clear(SKColors.Transparent);
XAML
<views:SKCanvasView ... BackgroundColor="Transparent" />
guessing here cause you forgot the screenshots,
what you probably want to do is using clipping
something like :
canvas.Clear();
canvas.ClipPath(path);
canvas.ResetMatrix();
canvas.DrawBitmap(...)
I have a gallery application that needs to zoom and pan. Instead of using default imageview , I found a sample touchmageview on internet and copied it. I called my images with TouchImageView and now i can zoom and pan the images that I called from my drawable folder. Then I added gallery to my project. Now the problem is that I can not fit the images to the screen.When I use scaletype.center then it fits the image to the screen but now zoom and pan features are not working. This is my gallerylistener ;
gallery.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
Toast.makeText(Display.this, "Your selected position = " + position, Toast.LENGTH_SHORT).show();
// show the selected Image
img.setScaleType(ScaleType.CENTER_INSIDE);
img.setImageResource(Imgid[position]);
}
});
As you see , if I add img.setScaleType(ScaleType.CENTER_INSIDE); then the TouchImageView class doesn't work and I am not able to zoom and pinch and pan etc.. It only display the image. When I delete this code , then I can zoom but then when I change the picture to another one , the new one has the previous image's size. But I want to fit them to the center. Is there any way to reset the scaletype before calling the new image ?
By the way I have only one imageview in xml.
There is a similar question on this link but the solution did not work for me.
how to get setScaleType(ImageView.ScaleType.FIT_CENTER) effect using setScaleType(ImageView.ScaleType.MATRIX)
I'm looking for a photo gallery for Windows Phone 7. Something that looks and works the same as the built-in photo viewer (slide photo's using a flick action, resize using pinch, drag). When you flick the image you can see it sliding to the next image...and snaps the list to that image.
I already built the resize and drag functionality for the images. I just can't figure out how to create the actual photo slider.
Can anyone point me into the right direction?
Things i've tried:
Pivot Viewer (doesn't work because it interferes with the drag functions of the image, haven't been able to disable the pivot viewer touch)
Plain listbox (can't find how to snap to the current image)
Thanks in advance
Actually I've implemented exactly what you are saying in one of my apps,
You need to use Silverlight Control TOolkit's gesture listener to capture Drag and Pinch from touch.
define a CompositeTransformation for your image and set it's scale (on pinch) and Offset (in drag).
Obviously when the image is not zoom, drag can trigger going to next image.
To make it feel smoother, you may want to define a storyboard on your page resources to use (instead of just settings Offset)
I hope it can help/
Drag handlers pseudo code for slider effect:
<Canvas>
<Image x:Name="imgImage" Source="{Binding ...}" Width="..." Height="...">
<Image.RenderTransform>
<CompositeTransform x:Name="imgImageTranslate" />
</Image.RenderTransform>
</Image>
</Canvas>
private void GestureListener_DragCompleted(object sender, DragCompletedGestureEventArgs e)
{
if (e.Direction == System.Windows.Controls.Orientation.Horizontal)
{
var abs = Math.Abs(PANEL_DRAG_HORIZONTAL);
if (abs > 75)
{
if (PANEL_DRAG_HORIZONTAL > 0) // MovePrevious;
else //MoveNext();
e.Handled = true;
}
}
}
double PANEL_DRAG_HORIZONTAL = 0;
private void GestureListener_DragDelta(object sender, DragDeltaGestureEventArgs e)
{
if (e.Direction == System.Windows.Controls.Orientation.Horizontal)
{
PANEL_DRAG_HORIZONTAL += e.HorizontalChange;
var baseLeft = -imgImage.Width / 2;
if (PANEL_DRAG_HORIZONTAL > 75) imgImageTranslate.OffsetX = baseLeft + PANEL_DRAG_HORIZONTAL;
else if (PANEL_DRAG_HORIZONTAL < -75) imgImageTranslate.OffsetX = baseLeft + PANEL_DRAG_HORIZONTAL;
else imgImageTranslate.OffsetX = baseLeft;
}
}
}
private void GestureListener_DragStarted(object sender, DragStartedGestureEventArgs e)
{
PANEL_DRAG_HORIZONTAL = 0;
}
What about using a ScrollViewer with horizontal orientation? Of course, you will have to manually detect user actions and implement the proper response (with a couple of properly set Storyboards).
Even a better approach would be writing your own custom control that will view images. A good place to start is this - a CoverFlow control in Silverlight. Once you get the idea how you can bind your image collection to a custom control, all you need is handle user gestures on the currently selected item.
HI all,
I wnt to develop an ImageViewer using qt. I m trying to resize big images by scaling them. My problem is , when i change the screen orientation some part of the image gets clipped and also if i open the image in landscape mode, by default the size of image remains small even when i change back to portrait mode. What am i Doin wrong?
Please help me out. Heres the code dat i hv written
ImageViewer::ImageViewer()
{
setAttribute(Qt::WA_DeleteOnClose);
QAction *back = new QAction(this);
back->setText(QString("Back"));
connect(back,SIGNAL(triggered()),this,SLOT(close()));
back->setSoftKeyRole(QAction::PositiveSoftKey);
addAction(back);
imageLabel = new QLabel();
imageLabel->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding);
imageLabel->setAlignment(/*Qt::AlignLeft|*/Qt::AlignCenter);
QWidget *widget = new QWidget;
layout=new QStackedLayout();
layout->addWidget(imageLabel);
widget->setLayout(layout);
setCentralWidget(widget);
}
void ImageViewer::showImage(QString filePath)
{
QImageReader reader;
reader.setFileName(filePath);
QSize imageSize = reader.size();
imageSize.scale(size(), Qt::KeepAspectRatio);
reader.setScaledSize(imageSize);
QImage image = reader.read();
imageLabel->setPixmap(QPixmap::fromImage(image));
imageLabel->adjustSize();
}
You should re-implement QLabel's resizeEvent or install event filter to it and handle QResizeEvent there
The content of showImage method should go to handler of a resize event.
Currently you are using size() of ImageViewer widget (which seems to be derived from QMainWindow), it's better to use imageLabel.size(); or the best QResizeEvent::size() as this will prevent a problem if you will change UI layout in future.