I am not able to figure out how to zoom the image displayed with the help of an item renderer.If i apply the Zoom effect on rollover ,the particular cell zooms the image with the scroll bars.Is their any other way of doing this without showing the scrollbars.
You'll need to duplicate the image and place it outside of the datagrid component. If it's inside the datagrid, it'll be forced into one of the rows. It might be helpful for you to look at the code for the DataGridDragProxy - it does does something sorta similar.
Related
I have dynamic list with 20~ cells.
I have 3 types of cells so i can't use Listview.
I am using ScrollView that contains StackLayout with the cell elements.
each cell element is also a StackLayout that contains some labels and buttons
the scrolling is smooth.
I have option in each cell to add image by a pressing a button inside the cell.
After the image is added, the scroll is getting very slow when arriving to the cell with the image.
when scrolling beyond the image, the scroll become smooth again
I have also tried TableView but the scrolling is not smooth when presenting the Cells (without adding the image)
How can i improve the rendering of the image ?
I have 3 types of cells so i can't use Listview.
Actually you can use a ListView, by using a DataTemplateSelector. As long as you have a collection containing all of the objects to be displayed, and each object in the collection indicates the cell type (usually because of it model's type), ListView with DataTemplateSelector will work great.
Whether you stick with ScrollView or move to ListView, look into FFImageLoading for displaying images if possible. While it doesn't solve all image display problems, it often does help with responsiveness and image size issues.
I am trying to create a grid layout of images kind of like how google images does it.
I want to add fixed sized images left to right, top to bottom but I am having trouble is figuring out when adding another image to a row would make it not fit and then decide that that images should be placed in a new row.
Also when the window resizes it should move images into/from rows based on how many it can fit in.
Ive got a scroll area with a grid layout in it which is fine if I know what can fit, but I can't figure out how to make it move items if say the window width is shrunk, and say an item needs to be moved down 1 row which moves other etc.
Assuming you are using QWidgets I'd suggest you to use QListView which does the layouting for free, if you want more control on how items are displayed use a QItemDelegate. For QListView the view mode should be set to QListView::IconMode so that you have a grid of items and not a list.
But if you are using QtQuick things are much easier, a GridView with Image delegates would do what you want really quickly and using GPU power to build you UI.
In qt, I have a form that contains among other things, a group with
A combo box
a checkbox
a spacer
a button
Based on some logic, I want sometimes to show another combo box... Where the spacer is, but smaller.
When I add it though, everything resizes automatically
I don't see a way to make it invisible, and yet keep items of the same size when I make it visible again.
I tried making it fixed size... But unless I use fixed sizes and positioning for everything, which I think is a bad idea, the items still move around when I change visibility.
It seems silly... But how can I make my little combo box show up instead of the spacer not next to it ? Spacers don't seem to have a name...
I would do
combo.setVisible(condition);
Spacer.setVisible(!condition);
Very easy... Except how do I access the spacer from code ?
My suggestion is to use a container QWidget instead of the spacer. Here is how it will look:
A combo box
a checkbox
a widget-container
a button
Widget-container is a QWidget with fixed size. Put your combo-box there and it will maintain it's size when you show/hide the combo-box.
Regarding your question (You will not need it but just to know in the future):
how do I access the spacer from code
You can create a spacer from code like this:
QSpacerItem* spacer = new QSpacerItem(0, 15, QSizePolicy::Fixed, QSizePolicy::Fixed);
layout->addItem(spacer);
...
Also you can get it from a layout if you know its index:
QLayoutItem* item = layout->itemAt(index);
But there is no such method as show/hide for layout items.
I'm using a spark ItemRenderer in a list with useVirtualLayout="true"
The itemRenderer has an image loaded in it.
When the list scrolls, and a new Item is brought into view - the image flickers, briefly showing the previous image in the itemrenderer.
When the itemrenderer is re-used, how can I prevent the flicker?
Is there an event when an itemrenderer is discarded? then I could hide the image or load a blank image.
Try this
A simple way to avoid Flickering images is to give a height according to the total images to show
example
if the List have vertical layout
myList.height = myList.dataProvider.length;
if the List have horizontal layout
myList.width = myList.dataProvider.length;
It depends on how you use the image. I tend to load the image and save its BitmapData ONCE!. Then you can directly use it without any flickering. You just have to inject some sort of ImageRespository into the renderer.
This can easily be done by listing to the rendererAdd event of the DataGroup and stuff the repo into the renderer.
I'm trying to make a Flex (Advanced)DataGrid component with some mechanism where the user can toggle the visibility of the columns. I've crudely implemented this by reading in the columns into the right-click menu, and when a column name is selected here, the visibility is toggled. It works, but it's not the most elegant solution.
Specifically, I'm trying to emulate the "datagrid" that Mozilla Thunderbird uses to display emails. Here is an image:
In the upper right, there is an icon over the scroll bar. If there is no scrollbar, the icon remains in the same place. When clicking the icon, it opens up a menu that shows all the possible columns, with the visible ones having a check mark next to them, like this:
Also, the scroll bar always appears under this button, never "pushing" it over into it's own column.
I'd like to re-create this in Flex. I believe the menu part and creating a column with a button headerRenderer is easy enough. But I can't figure out how (if at all possible) to do this with the scrollbar, because the scrollbar always seems to be "its own column". Any ideas or help would be appreciated. Thank you.
Ian
One dirty solution comes to mind. Create a component based on Canvas, then add an AdvancedDataGrid by overriding createChildren. Override updateDisplayList as well and add a button like the one in Thunderbird to the upper right of the Canvas. This will cause the button to appear over the DataGrid. Problemo solved?