Each Rectangle item is painted using either a solid fill color, specified using the color property, or a gradient, defined using a Gradient type and set using the gradient property.

If both a color and a gradient are specified, the gradient is used. You can add an optional border to a rectangle with its own color and thickness by setting the border. Set the color to "transparent" to paint a border without a fill color. You can also create rounded rectangles using the radius property. Since this introduces curved edges to the corners of a rectangle, it may be appropriate to set the Item::antialiasing property to improve its appearance.

The following example shows the effects of some of the common properties on a Rectangle item, which in this case is used to create a square:. Using the Item::antialiasing property improves the appearance of a rounded rectangle at the cost of rendering performance. You should consider unsetting this property for rectangles in motion, and only set it when they are stationary.

Used to decide if the Rectangle should use antialiasing or not. Antialiasing provides information on the performance implications of this property. Note: The width of the rectangle's border does not affect the geometry of the rectangle itself or its position relative to other items if anchors are used.

The following example shows rectangles with colors specified using hexadecimal and named color notation:. This property allows for the construction of simple vertical or horizontal gradients. Other gradients may be formed by adding rotation to the rectangle. The property also accepts gradient presets from QGradient::Preset. Note however that due to Rectangle only supporting simple vertical or horizontal gradients, any preset with an unsupported angle will revert to the closest representation.

See also Gradient and color. If radius is non-zero, the rectangle will be painted as a rounded rectangle, otherwise it will be painted as a normal rectangle. The same radius is used by all 4 corners; there is currently no way to specify different radii for different corners. Documentation contributions included herein are the copyrights of their respective owners. Qt and respective logos are trademarks of The Qt Company Ltd. All other trademarks are property of their respective owners.

Import Statement: import QtQuick 2. The default is true for Rectangles with a radius, and false otherwise.

Network Transparency

The width and color used to draw the border of the rectangle. A width of 1 creates a thin line. For no line, use a width of 0 or a transparent color.Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you may not be able to execute some actions.

Please download a browser that supports JavaScript, or enable it if it's disabled i. Is it possible to disable the transparency of an Image object in QML? Basically I'm loading an image and applying a heavy Gaussian blur on it.

The problem occurs when the image has certain areas which are transparent. The blur takes these transparent pixels into account and it results in the blur becoming weaker. Notice that the image is still distinguishable which it should not be at such a high blur However, if I replace the transparent parts with black in the original image, like this:. As such I would like to know if it is possible to disable transparency in the QML Image component which would essentially be compositing the transparent image on a colored background, and loading the new image.

I sorted it out by placing the Image inside an Item along with a black rectangle behind it. Applying Gaussian blur on the Item solves the issue. Qt Forum. Only users with topic management privileges can see it.

For example, this is the original image, When I apply Gaussian blur samples I get this: Notice that the image is still distinguishable which it should not be at such a high blur However, if I replace the transparent parts with black in the original image, like this: and then apply the same blur, I get the intended effect: As such I would like to know if it is possible to disable transparency in the QML Image component which would essentially be compositing the transparent image on a colored background, and loading the new image.

Reply Quote 0 1 Reply Last reply. Loading More Posts 2 Posts. Reply Reply as topic.Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you may not be able to execute some actions. Please download a browser that supports JavaScript, or enable it if it's disabled i. Dear all, I have an Image that it's a donut, and I would like to add a MouseArea that react only when the donut is touched and not react when the touch happens inside the hole because there is another object in the hole with its MouseArea.

How is it possible with QML?? This should be possible by using a custom QQuickItem which overrides the mouseEvent functions. Use the alpha channel of the image to decide if the mouse event gets accepted or not. Downside is that there is no way to get to the image through public API, so you would have to simply load it in your custom MouseArea.

QML Qt 138 - Introduction to QML

I have an idea to do this. It's a draft need some performance tweaks like don't grab the image every time if you click on it. QQuickItem does not have a grabWindow function. QQuickWindow has but that will include the background of the window and will thus most likely be fully opaque.

In Qt 5. If you know it is going to always be a torus, solve the torus function in the mouse handler and save the extra cost of the image :. Right, sorry my source is wrong i forgot the window. As I pointed out, grabWindow will include the window itself and will thus most likely be opaque and therefore not useful for the purpose of an AlphaMouseArea.

Qt Forum. How to make a MouseArea not react on transparent area of an Image This topic has been deleted. Only users with topic management privileges can see it. Thanks, Gianluca. Reply Quote 0 1 Reply Last reply. Loading More Posts 6 Posts.

Reply Reply as topic.The source of the image is specified as a URL using the source property. If you need to display animated images, use AnimatedSprite or AnimatedImage. If the width and height properties are not specified, the Image automatically uses the size of the loaded image. By default, specifying the width and height of the item causes the image to be scaled to that size. This behavior can be changed by setting the fillMode property, allowing the image to be stretched and tiled instead.

When the default OpenGL scene graph backend is in use, images can also be supplied in compressed texture files. The following container file formats are supported:. Note: Semi-transparent original images require alpha pre-multiplication prior to texture compression in order to be correctly displayed in Qt Quick.

This can be done with the following ImageMagick command line:. If the source URL indicates a non-existing local file or resource, the Image element attempts to auto-detect the file extension.

qml image transparency

If an existing file can be found by appending any of the supported image file extensions to the source URL, then that file will be loaded. If the search is unsuccessful, it attempts to search with the file extensions for the conventional image file types. For example:. This functionality facilitates deploying different image asset file types on different target platforms.

This can be useful in order to tune application performance and adapt to different graphics hardware. By default, locally available images are loaded immediately, and the user interface is blocked until loading is complete.

If a large image is to be loaded, it may be preferable to load the image in a low priority thread, by enabling the asynchronous property. If the image is obtained from a network rather than a local resource, it is automatically loaded asynchronously, and the progress and status properties are updated as appropriate.

Images are cached and shared internally, so if several Image items have the same sourceonly one copy of the image will be loaded. Note : Images are often the greatest user of memory in QML user interfaces. It is recommended that images which do not form part of the user interface have their size bounded via the sourceSize property. This is especially important for content that is loaded from external sources or provided by the user.

The default is 0. You can set it to a number between 0 and frameCount - 1 to display a different frame, if the image contains multiple frames. Most images have only one frame. Sets the horizontal and vertical alignment of the image. By default, the image is center aligned. The valid values for horizontalAlignment are Image.

AlignLeftImage. AlignRight and Image. The valid values for verticalAlignment are Image. AlignTopImage.

Qt Documentation

AlignBottom and Image. These properties hold the size of the image that is actually painted. In most cases it is the same as width and heightbut when using an Image.

PreserveAspectFit or an Image. PreserveAspectCrop paintedWidth or paintedHeight can be smaller or larger than width and height of the Image item. Specifies that images on the local filesystem should be loaded asynchronously in a separate thread.All visual items in Qt Quick inherit from Item. Although an Item object has no visual appearance, it defines all the attributes that are common across visual items, such as x and y position, width and height, anchoring and key handling support.

The Item type can be useful for grouping several items under a single root visual item. For example:. Key handling is available to all Item-based visual types via the Keys attached property. The Keys attached property provides basic signals such as pressed and releasedas well as signals for specific keys, such as spacePressed.

The example below assigns keyboard focus to the item and handles the left key via the general onPressed handler and the return key via the onReturnPressed handler:.

Item layouts can be mirrored using the LayoutMirroring attached property. This causes anchors to be horizontally reversed, and also causes items that lay out or position their children such as ListView or Row to horizontally reverse the direction of their layouts.

An Item will normally be rendered directly into the window it belongs to. However, by setting layer. Only the offscreen surface, a texture, will be then drawn into the window. If it is desired to have a texture size different from that of the item, this is possible using layer.

Resource Loading and Network Transparency in QML

To render only a section of the item into the texture, use layer. It is also possible to specify layer. In this case, the exterior will be padded with transparent pixels. The item will use linear interpolation for scaling if layer.

Mipmapping may improve visual quality of downscaled items. For mipmapping of single Image items, prefer Image::mipmap. When applying opacity to an item hierarchy the opacity is applied to each item individually. This can lead to undesired visual results when the opacity is applied to a subtree. Consider the following example:. A layer is rendered with the root item's opacity being 1, and then the root item's opacity is applied to the texture when it is drawn.

This means that fading in a large item hierarchy from transparent to opaque, or vice versa, can be done without the overlap artifacts that the normal item by item alpha blending has.

Here is the same example with layer enabled:. Setting layer.

In this example, we implement the shader effect manually. See ShaderEffect for more information about using effects. Note: layer.

When an item's layer is enabled, the scene graph will allocate memory in the GPU equal to width x height x 4. In memory constrained configurations, large layers should be used with care. In Qt Quick, because of the techniques already applied by the scene graph rendererthis will in most cases not be the case. Excessive draw calls are already reduced because of batching and a cache will in most cases end up blending more pixels than the original content.

The overhead of rendering to an offscreen and the blending involved with drawing the resulting texture is therefore often more costly than simply letting the item and its children be drawn normally. Also, an item using a layer can not be batched during rendering. This means that a scene with many layered items may have performance problems.

Layering can be convenient and useful for visual effects, but should in most cases be enabled for the duration of the effect and disabled afterwards. Defines the natural width or height of the Item if no width or height is specified. The default implicit size for most items is 0x0, however some items have an inherent implicit size which cannot be overridden, for example, Image and Text.Dynamic Object Management Internationalization.

For example if the qmldir file contains the line "World World. Whenever an object has a property of type URL QUrlassigning a string to that property will actually assign an absolute URL - by resolving the string against the URL of the document where the string is used.

Because of the declarative nature of QML and the asynchronous nature of network resources, objects which reference network resource generally change state as the network resource loads. For example, an Image with a network source will initially have a width and height of 0, a status of Loadingand a progress of 0. While the content loads, the progress will increase until the content is fully loaded from the network, at which point the width and height become the content size, the status becomes Readyand the progress reaches 1.

Applications can bind to these changing states to provide visual progress indicators where appropriate, or simply bind to the width and height as if the content was a local file, adapting as those bound values change. Note that when objects reference local files they immediately have the Ready status, but applications wishing to remain network transparent should not rely on this.

For example, using these facilities to access an on-line photography service would provide the QML application with URLs to photographs, which can be directly set on an Image source property. One of the URL schemes built into Qt is the "qrc" scheme.

This allows content to be compiled into the executable using The Qt Resource System. Using this, an executable can reference QML content that is compiled into the executable:. The content itself can then use relative URLs, and so be transparently unaware that the content is compiled into the executable. Documentation contributions included herein are the copyrights of their respective owners.

Documentation sources may be obtained from www. All other trademarks are property of their respective owners. Privacy Policy. Search index:. Home Network Transparency. A A A Print. Relative vs. Progressive Loading Because of the declarative nature of QML and the asynchronous nature of network resources, objects which reference network resource generally change state as the network resource loads.

Using this, an executable can reference QML content that is compiled into the executable: QDeclarativeView view; view. Limitations The import statement is only network transparent if it has an "as" clause. More specifically: import "dir" only works on local file systems import libraryUri only works on local file systems import "dir" as D works network transparently import libraryUrl as U works network transparently.This means that anywhere a URL source is expected, QML can handle remote resources as well as local ones, for example in the following image source:.

For example if the qmldir file contains the line "World World. Whenever an object has a property of type URL QUrlassigning a string to that property will actually assign an absolute URL - by resolving the string against the URL of the document where the string is used.

Because of the declarative nature of QML and the asynchronous nature of network resources, objects which reference network resource generally change state as the network resource loads. For example, an Image with a network source will initially have a width and height of 0, a status of Loadingand a progress of 0.

While the content loads, the progress will increase until the content is fully loaded from the network, at which point the width and height become the content size, the status becomes Readyand the progress reaches 1. Applications can bind to these changing states to provide visual progress indicators where appropriate, or simply bind to the width and height as if the content was a local file, adapting as those bound values change.

Note that when objects reference local files they immediately have the Ready status, but applications wishing to remain network transparent should not rely on this. For example, using these facilities to access an on-line photography service would provide the QML application with URLs to photographs, which can be directly set on an Image source property.

One of the URL schemes built into Qt is the "qrc" scheme.

qml image transparency

This allows content to be compiled into the executable using The Qt Resource System. Using this, an executable can reference QML content that is compiled into the executable:.

The content itself can then use relative URLs, and so be transparently unaware that the content is compiled into the executable. The following objects and properties are supported by the QML implementation:. Documentation contributions included herein are the copyrights of their respective owners.

Documentation sources may be obtained from www. All other trademarks are property of their respective owners. Privacy Policy. Relative vs.

qml image transparency

Progressive Loading Because of the declarative nature of QML and the asynchronous nature of network resources, objects which reference network resource generally change state as the network resource loads.


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