Vlayout provides rich layout features, which are presented in the form of a serial of layout attributes technically. Here we introduce these attributes.
Margin, padding have the similar concepts as normal Android system's margin and padding. There are several difference you should know:
- Here we say margin and padding, specifically mean
LayoutHelper's margin and padding, not theRecyclerView's. - A
RecyclerViewcould contains more than one layoutHelpers, which means eachLayoutHelperis able to host its own margin and padding value. LayoutHelper's margin and padding can coexist withRecyclerView's margin and padding.- Margin and padding is mainly supported by non-fix LayoutHelper.
For LayoutHelper，call
public void setPadding(int leftPadding, int topPadding, int rightPadding, int bottomPadding)
public void setMargin(int leftMargin, int topMargin, int rightMargin, int bottomMargin)
Actually, background color or background image has nothing to do with layout logic. But in our framework, all child views has the same parent which is RecyclerView. If you want to fill background to a certain area with a color or image, it's a hard job. Vlayout has done some effort to make it possible for non-fix LayoutHelper, so it's explained here.
Fill background with color, call
public void setBgColor(int bgColor)
Fill background with image,
First, provide a simple factory to produce ImageView to LayoutManager,
this.mLayoutManager.setLayoutViewFactory(new LayoutViewFactory() {
@Override
public View generateLayoutView(@NonNull Context context) {
return new XXImageView(context);
}
});
Second, set image load listeners to LayoutHelper,
baseHelper.setLayoutViewBindListener(new BindListener(imgUrl));
baseHelper.setLayoutViewUnBindListener(new UnbindListener(imgUrl));
private static class BindListener implements BaseLayoutHelper.LayoutViewBindListener {
private String imgUrl;
public BindListener(String imgUrl) {
this.imgUrl = imgUrl;
}
@Override
public void onBind(View layoutView, BaseLayoutHelper baseLayoutHelper) {
//loading image
}
}
private static class UnbindListener implements BaseLayoutHelper.LayoutViewUnBindListener {
private String imgUrl;
public UnbindListener(String imgUrl) {
this. imgUrl = imgUrl;
}
@Override
public void onUnbind(View layoutView, BaseLayoutHelper baseLayoutHelper) {
//cancel loading image
}
}
In order to uniform child view's height during layout, vlayout introduces aspectRatio. Generally the view's width is decided by LayoutHelper while its height is decided by the view itself, using aspectRatio allow LayoutHelper to decide view's height. Both LayoutHelper and LayoutParams of the view inside vlayout have this attribute. It generally means width/height ratio, but has slight difference in these two situations. The latter has a higher priority than the former.
- The aspectRatio defined by
LayoutHelpermeans the ratio of width of one entire row's view to height of this row's height. HereRecyclerView's margin padding andLayoutHelper's margin padding is not included in the width of entire row's view. - The aspectRatio defined in
VirtualLayoutManager.LayoutParamsmeans the ratio of width of this view to height of this view. The height calculated by this way will overrideLayoutHelper's calculation result, so it has higher priority.
For LayoutHelper, call
public void setAspectRatio(float aspectRatio)
For LayoutParams, call
((VirutalLayoutManager.LayoutParams) layoutParams).mAspectRatio
LinearLayoutHelper's attribute. LinearLayoutHelper performs like ListView, so as you know, dividerHeight is the gap between items.
For LinearLayoutHelper, call
public void setDividerHeight(int dividerHeight)
ColumnLayoutHelper and GridLayoutHelper's attribute, they both provide grid layout ability like GridLayoutManager. You are suggested to use GirdLayoutHelper since it is more powerful. By default, each column's width is equal and shares the available space. Setting weights allows each column's width occupies a certain percentage of available space. Just sounds like weight in LinearLayout.
This attribute is a float array, each item in array means the percentage of a column width. The sum of item value in array is 100, otherwise child view may be layouted outside the box. If there are four columns in this layout, the suggested length of weights is four, too. If length of weights array is larger than 4, the extra weight provided is ignored. If length of weights array is less than 4, the remaining views with no weight assigned share the remaining available space.
For ColumnLayoutHelper, GridLayoutHelper, call
public void setWeights(float[] weights)
GridLayoutHelper and StaggeredGridLayoutHelper's attribute, vGap defines the vertical gap between child views, hGap defines the horizontal gap between child views.
For GridLayoutHelper, StaggeredGridLayoutHelper, call
public void setHGap(int hGap)
public void setVGap(int vGap)
GridLayoutHelper's attribute, concept borrowed from system's GridLayoutManager. SpanCount specifies the column count, or grid count each line in other word. By default each item view in GridLayoutHelper occupies one grid, but with custom spanSizeLookup it allows one item view could occupy more than one grid space.
Setting spanCount call
public void setSpanCount(int spanCount)
Setting spanSizeLookup call
public void setSpanSizeLookup(SpanSizeLookup spanSizeLookup)
GridLayoutHelper's attribute. On the occasion of one line view's count is less than spanCount, if autoExpand is set to be true, these view will expand to fill all available space, otherwise they will leave some blank area.
public void setAutoExpand(boolean isAutoExpand)
StaggeredGridLayoutHelper's attribute, performs like spanCount in GridLayoutHelper.
public void setLane(int lane)
LayoutHelper with fix behavior may need an offset to four edges of parent container. For example, an activity has a vlayout container with fullscreen size, there's an title bar on top of vlayout's container which is not part of vlayout. While a view inside vlayout wants to be fixed at top of vlayout, so it needs an offset to top edge to avoid overlapping with title bar outside.
public void setAdjuster(FixAreaAdjuster adjuster)
FixLayoutHelper, ScrollFixLayoutHelper, FloatLayoutHelper's attributes, alignType defines the base position of fix area, there are four available values: TOP_LEFT, TOP_RIGHT, BOTTOM_LEFT, BOTTOM_RIGHT. x and y are the horizontal offset and vertical offset to this base position. The final offset is calculated with fixAreaAdjuster in addition as former mentioned.
TOP_LEFT: base position is top left corner of parent container,xis the offset from child view's left edge to parent's left edge,yis the offset from child view's top edge to parent's top edge;TOP_RIGHT: base position is top right corner of parent container,xis the offset from child view's right edge to parent's right edge,yis the offset from child view's top edge to parent's top edge;BOTTOM_LEFT: base position is bottom left corner of parent container,xis the offset from child view's left edge to parent's left edge,yis the offset from child view's bottom edge to parent's bottom edge;BOTTOM_RIGHT: base position is bottom right corner of parent container,xis the offset from child view's right edge to parent's right edge,yis the offset from child view's bottom edge to parent's bottom edge;
Setting alignType call
public void setAlignType(int alignType)
Setting offset call
public void setX(int x)
public void setY(int y)
ScrollFixLayoutHelper's attribute, there are three available values: SHOW_ALWAYS, SHOW_ON_ENTER, SHOW_ON_LEAVE.
SHOW_ALWAYS: in this way,ScrollFixLayoutHelperperforms the same asFixLayoutHelper;SHOW_ON_ENTER: in this way, the child view inLayoutHelperdoes not show by default. It shows only when the page scroll to its position.SHOW_ON_LEAVE: in this way, the child view inLayoutHelperdoes not show by default, either. It shows only when the page scroll over its position.
public void setShowType(int showType)
StickyLayoutHelper's attribute, when child view's position is inside the screen visible area, the child view scrll with whole page; when child view position scrolls outside the screen, this LayoutHelper will fix the at top(stickyStart = true) or bottom(stickyStart = false). The fix position is also affected by offset value.
public void setStickyStart(boolean stickyStart)
public void setOffset(int offset)