Is there a way to show a picture/image in a QToolTip?
I want to show small images of keyboard-buttons to explain the user which buttons/shortcuts he can use on that specific widget.
You can easily show images with the following html code:
QToolTip::showText(QCursor::pos(), "<img src=':/icon.png'>Message", this, QRect(), 5000);
This example will show a tooltip with the image from Qt resources and the text for 5 seconds.
For more details, you can see this video: https://youtu.be/X9JD8gKGZ00
Edit1:
If you want to show an image from memory, you can save the QImage/QPixmap to memory (preferably using some lossless compression like PNG) and convert it to base 64 and load it with the html code, like this:
QImage icon = QImage(10, 10, QImage::Format_ARGB32);
icon.fill(QColor(255, 0, 0, 100));
QByteArray data;
QBuffer buffer(&data);
icon.save(&buffer, "PNG", 100);
QString html = QString("<img src='data:image/png;base64, %0'>Message").arg(QString(data.toBase64()));
QToolTip::showText(QCursor::pos(), html, this, QRect(), 5000);
Edit2: Corrected the html string as #Damon Lynch suggests.
With respect to the HTML string, the Python 3 / PyQt equivalent of user2014561's excellent solution to displaying in memory images is like this, assuming a QPixmap (a QImage will work the same):
buffer = QBuffer()
buffer.open(QIODevice.WriteOnly)
pixmap.save(buffer, "PNG", quality=100)
image = bytes(buffer.data().toBase64()).decode()
html = '<img src="data:image/png;base64,{}">'.format(image)
Related
How do i increase the size of a Rich Text on the click of a button ?
I have a QTextEdit box with Rich text pasted in it.On the click of a + [ui button] i need to increase the font size of all the text inside it. Any idea on how to do that ?
Solution
This is what you should do inside the slot :
//-------------------------desired format-------------------------------
qreal pointSize = 40; // 40 for example, you can parameterize it
QTextCharFormat format;
format.setFontPointSize(pointSize);
//----------------------------------------------------------------------
ui->textEdit->selectAll();
// ^^^^^^^^^^^ You ask for all text in the textedit
// But remember partially change with mouse selection is also doable
ui->textEdit->mergeCurrentCharFormat(format);
(P.S. ui->textEdit is a pointer to QTextEdit)
The key point is to create an instance of QTextCharFormat to set the "partial" information of the font (Ex: size information only) and use QTextEdit::mergeCurrentCharFormat to merge the original format with the new format.
For example:
After merging by the operations above, the color, font...etc except size will be retained:
You can use the QTestEdit::setCurrentFont() function. For example:
QTextEdit te;
QFont f = te.currentFont();
int oldPointSize = f.pointSize();
int newPointSize = oldPointSize + 10;
f.setPointSize(newPointSize);
te.setCurrentFont(f);
te.setText("Test");
te.show();
I have developed a small GUI in C++/Qt, I would like to know a fast way to test if image loaded is grayscale. In practise, when I load a grayscale image of gif format, I want it to be recognized as a grayscale image with depth()=8, and when I load a colored gif image, the depth of QImage would be 32.
Here's my open method :
void ImageViewer::open()
{
int status_off = 0;
fileName = QFileDialog::getOpenFileName(this, tr("Open File"), QDir::currentPath());
if (!fileName.isEmpty()) {
current_qimage = QImage(fileName);
if (current_qimage.isNull()) {
QMessageBox::information(this, tr("Image Viewer"),
tr("Cannot load %1.").arg(fileName));
return;
}
updateStatus(status_off);
// Image is colored with depth=8
if (current_qimage.depth()/8 != 4)
{rgblum_status = 0;}
else // Image is grayscale with depth=32
{rgblum_status = 1;}
loadImage();
}
}
From my first test, it seems that current_qimage, in current_qimage = QImage(fileName); inherits firstly from the format (gif here) before the contents of the image. Therefore, QImage has in two cases a depth() equal to 32.
How to make the difference between these two gif images (one grayscale and the other colored) ?
The QImage class has a function that you can call to test if the image is grayscale or not: QImage::isGrayscale(). It works for both 8-bit color table indexed images and 32-bit images.
Working on allowing the upload of images which can range in a variety of size, then allowing to crop a predefined area of the image for a thumbnail.
The thumbnail size is predefined to 150x150. Using the Jcrop.js tool to select a section of the image.
Problem:
When displaying the uploaded image in a smaller size than the original image by implementing set height/width on the image rendered, then there is a scale factor that comes into play when selecting an area to crop.
You either have to scale down the cropping area proportionately or you have to scale the image in relation to the actual image's size in comparison to its displayed size.
Question:
How do I figure out the scale of the browser displayed image vs. original image? I am currently using the following code to save the image, but how would I take into consideration the scaling?
public static Image CropImage(Image originalImage, int x, int y, int width, int height)
{
var bmp = new Bitmap(width, height);
bmp.SetResolution(originalImage.HorizontalResolution, originalImage.VerticalResolution);
using (var graphic = Graphics.FromImage(bmp))
{
graphic.SmoothingMode = SmoothingMode.AntiAlias;
graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphic.PixelOffsetMode = PixelOffsetMode.HighSpeed;
graphic.DrawImage(originalImage, new Rectangle(0, 0, width, height), x, y, width, height, GraphicsUnit.Pixel);
return bmp;
}
}
Bonus Question:
Another problem I discovered, is that there seems to be no efficient way to transfer the original file's ImageFormat when creating a new Bitmap which creates a ImageFormatMemoryBMP and when you attempt to call Bitmap.Save(memorystream, original rawformat) it will blow up. And bitmap RawFormat has no setter.
So how can you set the format on a new bitmap?
I think perhaps that this problem is solved purely on the front end, no need to use any server side for this.
Jcrop has a built in scale factor handler.
http://deepliquid.com/content/Jcrop_Sizing_Issues.html
Now you can use this in two ways, as I understand it. Either to 'resize' the image for you on the front end using 'box sizing', or you can tell it the 'truesize' of the image and it will work out the scale factor and handle the coordinates for you on it's own.
Box sizing
$('#cropbox').Jcrop({ boxWidth: 450, boxHeight: 400 });
True Size
$.Jcrop('#cropbox',{ trueSize: [500,370] });
Using the true size method you will need to invoke jcrop using the api method:
http://deepliquid.com/content/Jcrop_API.html#API_Invocation_Method
var jcrop_api,
options = { trueSize: [500,370] };
$('#target').Jcrop(options,function(){
jcrop_api = this;
});
Good luck!
I need to do something similar to QPainter::drawImage, but drawing a triangle part of the given picture (into a triangular region of my widget) instead of working with rectangles.
Any idea how I could do that, besides painfully trying to redraw every pixel?
Thanks for your insights!
If it is feasible for you to use a QPixmap instead of a QImage, you can set a bitmap mask for the QPixmap which defines which of the pixels are shown and which are transparent:
myPixmap->setMask(myTriangleMask);
painter->drawPixmap(myPixmap);
Here is another solution based on QImage:
MaskWidget::MaskWidget(QWidget* parent) : QWidget(parent) {
img = QImage("Sample.jpg"); // The image to paint
mask = QImage("Mask.png"); // An indexed 2-bit colormap image
QPainter imgPainter(&img);
imgPainter.drawImage(0, 0, mask); // Paint the mask onto the image
}
void MaskWidget::paintEvent ( QPaintEvent * event ) {
QPainter painter(this);
painter.drawImage(10, 10, img);
}
Mask.png is an image file with the same size as Sample.jpg. It contains an alpha channel to support transparency. You can create this file easily with The GIMP, for example. I added an alpha channel, changed all areas I want to have painted to transparent and all other areas to white. To reduce the size, I finally converted it to an indexed 2-bit image.
You could even create the mask image programmatically with Qt, if you need your triangle be computed based on various parameters.
I need to find a way to "upsample" text from 72dpi (screen) to 300dpi (print) for rendered client generated text. This is a true WYSIWYG application and we're expecting a ton of traffic so client side rendering is a requirement. Our application has several fonts, font sizes, colors, alignments the user can modify in a textarea. The question is how to convert 72dpi to 300dpi. We have the editior complete, we just need to make 300dpi versions of the textarea.
MY IDEA
1) Get textarea and increase the height, width, and font size by 300/72. (if ints are needed on font size I may need to increase the font then down-sample to the height/width)
2) use BitmapUtil.getSnapshot on the textarea to get a rendered version of the text
THE QUESTION
How can I render text inside of a textarea without the component lifecycle? Imagine:
var textArea:TextArea = new TextArea();
textArea.text = "This is a test";
var bmd:BitmapData = textArea.render();
Like Flextras said, width/height has nothing to do with DPI, unless you actually zoom into the application by 4.16X. If your application all has vector based graphics, it shouldn't be a problem. Plus, the concept of DPI is lost in any web application until you're trying to save/print a bitmap.
It's definitely possible, but you'll have to figure it on your own.
To ask a question another way, it is possible to create a TextArea in
memory which I can use the BitmapUtil.getSnapshot() function to
generate a BitmapData object
Technically, all components are in memory. What you want to do, I believe, is render a component without adding it to a container.
We do exactly this for the watermark on Flextras components. Conceptually we created a method to render the instance; like this:
public function render(argInheritingStyles : Object):void{
this.createChildren();
this.childrenCreated();
this.initializationComplete();
this.inheritingStyles = argInheritingStyles;
this.commitProperties();
this.measure();
this.height = this.measuredHeight;
this.width = this.measuredWidth;
this.updateDisplayList(this.unscaledWidth,this.unscaledHeight);
}
The method must be explicitly called. Then you can use the 'standard' procedure for turning the component into a bitmap. I think we use a Label; but the same approach should work on any given component.
Here is the final method I used to solve the problem of creating a printable version of the text and style of a Spark TextArea component. I ended up placing the custom component TextAreaRenderer (see below) in the MXML and setting the visibility to false. Then using the reference to this component to process any text field (renderObject) and get back a BitmapData object.
public class TextAreaRenderer extends TextArea implements IAssetRenderer
{
public function render(renderObject:Object, dpi:int = 300):BitmapData{
// CAST THE OBJECT
//.................
var userTextArea:TextArea = TextArea(renderObject);
// SCALE IS THE DIVISION OF THE NEW DPI OVER THE SCREEN DPI 72
//............................................................
var scale:Number = dpi / 72;
// COPY THE USER'S TEXT AREA INTO THE OFFSCREEN TEXT AREA
//.......................................................
this.text = userTextArea.text; // the actual text
this.height = Math.floor(userTextArea.height * scale); // scaled height
this.width = Math.floor(userTextArea.width * scale); // scaled width
// GET THE LAYOUT FORMATS AND COPY TO OFFSCREEN
// - the user's format = userTextAreaLayoutFormat
// - the hidden format = thisLayoutFormat
//...............................................
var editableLayoutProperties:Array = ['fontSize', 'fontFamily', 'fontWeight', 'fontStyle', 'textAlign', 'textDecoration', 'color']
userTextArea.selectAll();
var userTextAreaLayoutFormat:TextLayoutFormat = userTextArea.getFormatOfRange();
this.selectAll();
var thisLayoutFormat:TextLayoutFormat = this.getFormatOfRange();
for each(var prop:String in editableLayoutProperties){
thisLayoutFormat[prop] = userTextAreaLayoutFormat[prop];
}
// SCALE THE FONT SIZE
//....................
thisLayoutFormat.fontSize = thisLayoutFormat.fontSize * scale;
// SET THE FORMAT BACK IN THE TEXT BOX
//...................................
this.setFormatOfRange(thisLayoutFormat);
// REDRAW THE OFFSCREEN
// RETURN THE BITMAP DATA
//.......................
this.validateNow();
return BitmapUtil.getSnapshot(this);
}
}
Then calling the TextAreaRenderer after the text area is changed to get a scaled up bitmap.
// COPY THE DATA INTO THE OFFSCREEN COMPONENT
//............................................
var renderableComponent:IAssetRenderer = view.offScreenTextArea;
return renderableComponent.render(userTextArea, 300);
Thanks to the advice from www.Flextras.com for working through the issue with me.