I'm using Canvas for drawing in my Android application. But the result has bad quality (see the picture)
So, canvas drawing don't draw additional pixels with more dark color between "stairs pixels" for smoothing.
Like this
But I'm interesting how to do it.
Are there some preferences or methods for smoothing the picture? Thanx!
Edited: I've founded here
Use the ANTI-ALIAS flag for drawing smooth edges.
Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
//or
Paint p = new Paint();
p.setAntiAlias(true);
Related
Im making a Drawing/Editing program. I have made a drawing tool, using this code on the MouseMove event:
If down = True Then
Using br = New SolidBrush(Color.FromArgb(ColorA, ColorR, ColorG, ColorB))
GFX.FillEllipse(br, e.X, e.Y, size, size)
End Using
End If
GFX is graphics from a bitmap called IMG.
IMG is projected on a PictureBox.
The color integers are for the color channels, ColorA is for the alpha channel.
The down boolean is to check if the mouse is down.
SolidBrush br is the brush used to render the color of the stroke
e is MouseEventArgs
Now that I explained the code I will head on the problem that im facing:
I tried to draw a cricle with the drawing tool and I've noticed the "dots" were spaced out. It seems its more spaced out if the mouse is moving at a fast speed.
Do I need to get the raw input from the mouse? I really don't know, so how do I fix this?
Thanks.
When I am using QScatterSeries, I can very easily draw point at (x, y). However, instead of points I would like to draw short lines, like in the figure below. How can I get about doing so?
I tried using RectangleMarker, but it just draws a fat square. I would prefer a thin line about 2px wide and 20px in height.
Is there a way I can add custom marker shapes?
Here are the code and the settings I use to transform my points into lines :
//create scatter series to draw point
m_pSeries1 = new QtCharts::QScatterSeries();
m_pSeries1->setName("trig");
m_pSeries1->setMarkerSize(100.0);
//draw a thin rectangle (50 to 50)
QPainterPath linePath;
linePath.moveTo(50, 0);
linePath.lineTo(50, 100);
linePath.closeSubpath();
//adapt the size of the image with the size of your rectangle
QImage line1(100, 100, QImage::Format_ARGB32);
line1.fill(Qt::transparent);
QPainter painter1(&line1);
painter1.setRenderHint(QPainter::Antialiasing);
painter1.setPen(QColor(0, 0, 0));
painter1.setBrush(painter1.pen().color());
painter1.drawPath(linePath);
//attach your image of rectangle to your series
m_pSeries1->setBrush(line1);
m_pSeries1->setPen(QColor(Qt::transparent));
//then use the classic QtChart pipeline...
You can play the marker size, the dimension of the image and the drawing pattern in the painter to adapt the size and shape of the rectangle to obtain a line.
In the picture, it's the black line. As you can see you can repeat the process for other series.
Keep in mind that you cannot use the openGL acceleration:
m_pSeries0->setUseOpenGL(true);
My work is based on the QtCharts/QScatterSeries example : QScatterSeries example
Hope it will help you.
Florian
I implemented a little drawing function into my app with CreateJS like so:
var currentPosition = this.posOnStage(event);
var drawing = container.getChildByName('drawing');
drawing.graphics.ss(this.brushSize, "round").s(this.brushColor);
drawing.graphics.mt(this._lastMousePosition.x, this._lastMousePosition.y);
drawing.graphics.lt(currentPosition.x, currentPosition.y);
drawing.alpha = this.brushAlpha;
container.updateCache(this.enableErasing ? "destination-out" : "source-over");
drawing.graphics.clear();
this._lastMousePosition = this.posOnStage(event);
As you can see, the alpha value of this drawing can change. Sadly you can draw over a point you once did draw, so when you draw over a point multiple times the alpha effect will go away. Any idea how to solve this ?
Thanks :)
EDIT:
I tried it like gskinner and Lanny 7 proposed, but it didn't work. I attached a image so you can see the problem.
As suggested by Lanny, apply the alpha to the actual stroke, not to the Shape. You can use Graphics methods to help with this.
For example:
// set the brush color to red with the current brush alpha:
this.brushColor = createjs.Graphics.getRGB(255, 0, 0, this.brushAlpha);
I am trying to use mask on my QWidget. I want to overlay existing widget with row of buttons - similar to Skype
Notice that these buttons don't have jagged edges - they are nicely antialiased and widget below them is still visible.
I tried to accomplish that using Qt Stylesheets but on pixels that should be "masked out" was just black colour - it was round button on black, rectangular background.
Then I tried to do this using QWidget::mask(). I used following code
QImage alpha_mask(QSize(50, 50), QImage::Format_ARGB32);
alpha_mask.fill(Qt::transparent);
QPainter painter(&alpha_mask);
painter.setBrush(Qt::black);
painter.setRenderHint(QPainter::Antialiasing);
painter.drawEllipse(QPoint(25,25), 24, 24);
QPixmap mask = QPixmap::fromImage(alpha_mask);
widget.setMask(mask.mask());
Sadly, it results in following effect
"Edges" are jagged, where they should be smooth. I saved generated mask so I could investigate if it was the problem
it wasn't.
I know that Linux version of Skype does use Qt so it should be possible to reproduce. But how?
One possible approach I see is the following.
Prepare a nice high resolution pixmap with the circular button icon over transparent background.
Paint the pixmap on a square widget.
Then mask the widget leaving just a little bit of margin beyond the border of the circular icon so that the widget mask jaggedness won't touch the smooth border of the icon.
I managed to get a nice circular button with not so much code.
Here is the constructor of my custom button:
Button::Button(Type t, QWidget *parent) : QPushButton(parent) {
setIcon(getIcon(t));
resize(30,30);
setMouseTracking(true);
// here I apply a centered mask and 2 pixels bigger than the button
setMask(QRegion(QRect(-1,-1,32,32),QRegion::Ellipse));
}
and in the style sheet I have the following:
Button {
border-radius: 15px;
background-color: rgb(136, 0, 170);
}
With border-radius I get the visual circle and the mask doesn't corrupt the edges because it is 1 pixel away.
You are using the wrong approach for generating masks. I would generate them from the button images themselves:
QImage image(widget.size(), QImage::Format_Alpha8);
widget.render(&image);
widget.setMask(QBitmap::fromImage(image.createMaskFromColor(qRgba(0, 0, 0, 0))));
I'm trying to find a way to mark the border of a QGraphicsScene, and make it resizable inside a QGraphicsView, to create something similar to Microsoft Paint.
In other words, my current QGraphicsView looks like this:
But my image is only this big, as indicated by the red box:
I want my QGraphicsView to be like this (the little black boxes are cornergrabbers for resizing the canvas):
Functionally, I want it to be similar to MS Paint:
The canvas (scene) is resizable, and the scrollbars on the window (view) appear when needed. The blue background color (solid gray background) appears behind the canvas.
How would I go about accomplishing this?
To try to get the grey background, I've been experimenting with QGraphicsView.setBackgroundBrush() and QGraphicsScene.setBackgroundBrush(). I've learned that QGraphicsView's background brush completely overrides QGraphicsScene's background brush if one is set. Even if I only set the background brush for QGraphicsScene, that background brush extends over the image's original boundaries.
Here is a link to my test code.
Help is appreciated!
I have to struggle with your constructors...dunno if it works on Windows, but have to make it to work with Linux. Try :
def setPixmap(self, pixmap):
if self.pixmap_item:
self.removeItem(self.pixmap_item)
self.pixmap_item = self.addPixmap(pixmap)
self.setPixBackGround()
def setPixBackGround(self):
# put Background rect for image
pixR = self.pixmap_item.pixmap().rect()
bgRectangle = self.addRect(pixR.x()-10, pixR.y()-10,
pixR.width()+20, pixR.height()+20)
# set color and Z value to put it behind image
bgColor = QColor(58, 176, 176)
bgRectangle.setBrush(bgColor)
bgRectangle.setZValue(-.1)
# take coordinates for brabbers
bgR = bgRectangle.rect()
grab1R = QRect(-5,-5,10,10)
# put grabbers as wish...
grab1 = self.addRect(grab1R)
grab1.setPos(bgR.topLeft())
grab2 = self.addRect(grab1R)
grab2.setPos(bgR.topRight())
# ....etc....