I've successfully implemented a Image Viewer (for DICOM) in Qt. I can see the image and I can zoom in and out correctly.
Now, I want to see scroll bars if the image is too big to show when I zoom in.
I've used the UI. I placed a QScrollArea. Inside, the QLabel. The verticalScrollBarPolicy is ScrollBarAsNeeded. The horizontalScrollBarPolicy is ScrollBarAsNeeded.
The problem is: it doesn't work. I zoom in, but no scrollbar appears.
Second try: using a layout inside the QScrollArea.
So now there's a QWidget between the QScrollArea and the QLabel: a horizontal layout. Opened the same image, now I can see a vertical scroll bar on the right. The image is streched from left to right. When I zoom the image gets its correct proportion.
BUT... I zoom out and the scroll bar is the same, even if I can see the whole image. The horizontal scroll bar never appears.
Resizing the QLabel doesn't seem to affect. But if I resize the QScrollArea (resizing the main window) the horizontal scroll bar appears.
I've been checking some numbers:
In the QScrollArea
- Its size changes: below 599 width (why this number? I can't see it anywhere) the horizontal bar appears.
- sizeHint() always returns the same values: 33x41
In the QLabel
- The dimensions change, but that doesn't affect.
- sizeHint() always returns the same values: 560x1558
Here is the code in XML from the UI designer:
<widget class="QWidget" name="centralWidget">
<property name="autoFillBackground">
<bool>false</bool>
</property>
<layout class="QVBoxLayout" name="verticalLayout">
<property name="margin">
<number>0</number>
</property>
<item>
<widget class="QScrollArea" name="scrollArea">
<property name="widgetResizable">
<bool>true</bool>
</property>
<property name="alignment">
<set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignTop</set>
</property>
<widget class="QWidget" name="scrollAreaWidgetContents">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>637</width>
<height>649</height>
</rect>
</property>
<layout class="QHBoxLayout" name="horizontalLayout_2">
<item>
<widget class="QLabel" name="miImagen">
<property name="sizePolicy">
<sizepolicy hsizetype="Preferred" vsizetype="Preferred">
<horstretch>0</horstretch>
<verstretch>0</verstretch>
</sizepolicy>
</property>
<property name="autoFillBackground">
<bool>true</bool>
</property>
<property name="scaledContents">
<bool>true</bool>
</property>
<property name="alignment">
<set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignTop</set>
</property>
</widget>
</item>
</layout>
</widget>
</widget>
</item>
</layout>
</widget>
What am I missing? Thank you.