CanvasWidget
touchgfx/widgets/canvas/CanvasWidget.hpp
Class for drawing complex polygons on the display using CanvasWidgetRenderer. The CanvasWidget is used by passing it to a Canvas object, drawing the outline of the object and then having CanvasWidget render the outline on the display using the assigned painter.
Inherits from: Widget, Drawable
Inherited by: AbstractGraphElement, AbstractShape, Circle, Line
Public Functions
| CanvasWidget() | |
| virtual void | draw(const Rect & invalidatedArea) const |
| Draws the given invalidated area. | |
| virtual bool | drawCanvasWidget(const Rect & invalidatedArea) const =0 |
| Draw canvas widget for the given invalidated area. | |
| virtual uint8_t | getAlpha() const |
| Gets the current alpha value of the widget. | |
| virtual Rect | getMinimalRect() const |
| Gets minimal rectangle containing the shape drawn by this widget. | |
| const AbstractPainter * | getPainter() const |
| Gets the current painter for the CanvasWidget. | |
| virtual Rect | getSolidRect() const |
| Gets the largest solid (non-transparent) rectangle. | |
| virtual void | invalidate() const |
| Invalidates the area covered by this CanvasWidget. | |
| virtual void | setAlpha(uint8_t newAlpha) |
| Sets the opacity (alpha value). | |
| void | setPainter(const AbstractPainter & painter) |
| Sets a painter for the CanvasWidget. | |
Protected Attributes
| uint8_t | alpha |
| The Alpha for this CanvasWidget. | |
Additional inherited members
Public Functions inherited from Widget
| virtual void | getLastChild(int16_t , int16_t , Drawable ** last) |
| Since a Widget is only one Drawable, Widget::getLastChild simply yields itself as result, but only if the Widget isVisible and isTouchable. | |
Public Functions inherited from Drawable
| void | center() |
| Centers the Drawable inside its parent. | |
| void | centerX() |
| Center the Drawable horizontally inside its parent. | |
| void | centerY() |
| Center the Drawable vertically inside its parent. | |
| virtual void | childGeometryChanged() |
| This function can be called on parent nodes to signal that the size or position of one or more of its children has changed. | |
| Drawable() | |
| Initializes a new instance of the Drawable class. | |
| void | drawToDynamicBitmap(BitmapId id) |
| Render the Drawable object into a dynamic bitmap. | |
| void | expand(int margin =0) |
| Expands the Drawable to have the same size as its parent with a given margin around the edge. | |
| Rect | getAbsoluteRect() const |
| Helper function for obtaining the rectangle this Drawable covers, expressed in absolute coordinates. | |
| virtual Drawable * | getFirstChild() |
| Function for obtaining the first child of this drawable if any. | |
| int16_t | getHeight() const |
| Gets the height of this Drawable. | |
| virtual void | getLastChild(int16_t x, int16_t y, Drawable ** last) =0 |
| Function for obtaining the the last child of this drawable that intersects with the specified point. | |
| Drawable * | getNextSibling() |
| Gets the next sibling node. | |
| Drawable * | getParent() const |
| Returns the parent node. | |
| const Rect & | getRect() const |
| Gets the rectangle this Drawable covers, in coordinates relative to its parent. | |
| virtual Rect | getSolidRectAbsolute() |
| Helper function for obtaining the largest solid rect (as implemented by getSolidRect()) expressed in absolute coordinates. | |
| virtual void | getVisibleRect(Rect & rect) const |
| Function for finding the visible part of this drawable. | |
| int16_t | getWidth() const |
| Gets the width of this Drawable. | |
| int16_t | getX() const |
| Gets the x coordinate of this Drawable, relative to its parent. | |
| int16_t | getY() const |
| Gets the y coordinate of this Drawable, relative to its parent. | |
| virtual void | handleClickEvent(const ClickEvent & event) |
| Defines the event handler interface for ClickEvents. | |
| virtual void | handleDragEvent(const DragEvent & event) |
| Defines the event handler interface for DragEvents. | |
| virtual void | handleGestureEvent(const GestureEvent & event) |
| Defines the event handler interface for GestureEvents. | |
| virtual void | handleTickEvent() |
| Called periodically by the framework if the Drawable instance has subscribed to timer ticks. | |
| virtual void | invalidateContent() const |
| Tell the framework that the contents of the Drawable needs to be redrawn. | |
| virtual void | invalidateRect(Rect & invalidatedArea) const |
| Request that a region of this drawable is redrawn. | |
| bool | isTouchable() const |
| Gets whether this Drawable receives touch events or not. | |
| bool | isVisible() const |
| Gets whether this Drawable is visible. | |
| virtual void | moveRelative(int16_t x, int16_t y) |
| Moves the drawable. | |
| virtual void | moveTo(int16_t x, int16_t y) |
| Moves the drawable. | |
| virtual void | setHeight(int16_t height) |
| Sets the height of this drawable. | |
| void | setPosition(const Drawable & drawable) |
| Sets the position of the Drawable to the same as the given Drawable. | |
| void | setPosition(int16_t x, int16_t y, int16_t width, int16_t height) |
| Sets the size and position of this Drawable, relative to its parent. | |
| void | setTouchable(bool touch) |
| Controls whether this Drawable receives touch events or not. | |
| void | setVisible(bool vis) |
| Controls whether this Drawable should be visible. | |
| virtual void | setWidth(int16_t width) |
| Sets the width of this drawable. | |
| void | setWidthHeight(const Bitmap & bitmap) |
| Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates). | |
| void | setWidthHeight(const Drawable & drawable) |
| Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates). | |
| void | setWidthHeight(const Rect & other) |
| Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates). | |
| void | setWidthHeight(int16_t width, int16_t height) |
| Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates). | |
| virtual void | setX(int16_t x) |
| Sets the x coordinate of this Drawable, relative to its parent. | |
| void | setXY(const Drawable & drawable) |
| Sets the x and y coordinates of this Drawable. | |
| void | setXY(int16_t x, int16_t y) |
| Sets the x and y coordinates of this Drawable, relative to its parent. | |
| virtual void | setY(int16_t y) |
| Sets the y coordinate of this Drawable, relative to its parent. | |
| virtual void | translateRectToAbsolute(Rect & r) const |
| Helper function for converting a region of this Drawable to absolute coordinates. | |
| virtual | ~Drawable() |
| Finalizes an instance of the Drawable class. | |
Protected Attributes inherited from Drawable
| Drawable * | nextSibling |
| Pointer to the next Drawable. | |
| Drawable * | parent |
| Pointer to this drawable's parent. | |
| Rect | rect |
| The coordinates of this Drawable, relative to its parent. | |
| bool | touchable |
| True if this drawable should receive touch events. | |
| bool | visible |
| True if this drawable should be drawn. | |
Public Functions Documentation
CanvasWidget
draw
Draws the given invalidated area.
If the underlying CanvasWidgetRenderer fail to render the widget (if the widget is too complex), the invalidated area is cut into smaller slices (horizontally) which are then drawn separately. If drawing a single raster line fails, that line is considered too complex and skipped (it is left blank/transparent) and drawing continues on the next raster line.
If drawing has failed at least once, which means that the number of horizontal lines draw has been reduced, the number of successfully drawn horizontal lines is remembered for the next invocation of draw(). A future call to draw() would then start off with the reduced number of horizontal lines to prevent potentially drawing the canvas widget in vain, as happened previously in draw().
| invalidatedArea | The invalidated area. |
Note
Subclasses of CanvasWidget should implement drawCanvasWidget(), not draw(). The term "too complex" means that the size of the buffer (assigned to CanvasWidgetRenderer using CanvasWidgetRenderer::setupBuffer()) is too small.
Reimplements: touchgfx::Drawable::draw
Reimplemented by: touchgfx::GraphElementGridBase::draw, touchgfx::GraphElementVerticalGapLine::draw, touchgfx::GraphElementHistogram::draw, touchgfx::GraphElementBoxes::draw, touchgfx::GraphLabelsBase::draw, touchgfx::GraphTitle::draw
drawCanvasWidget
| virtual bool drawCanvasWidget | ( | const Rect & | invalidatedArea | ) | |
Draw canvas widget for the given invalidated area.
Similar to draw(), but might be invoked several times with increasingly smaller areas to due to memory constraints from the underlying CanvasWidgetRenderer.
| invalidatedArea | The invalidated area. |
true if the widget was drawn properly, false if not.
Reimplemented by: touchgfx::AbstractGraphElementNoCWR::drawCanvasWidget, touchgfx::GraphTitle::drawCanvasWidget, touchgfx::AbstractShape::drawCanvasWidget, touchgfx::Circle::drawCanvasWidget, touchgfx::Line::drawCanvasWidget, touchgfx::GraphElementArea::drawCanvasWidget, touchgfx::GraphElementLine::drawCanvasWidget, touchgfx::GraphElementDots::drawCanvasWidget, touchgfx::GraphElementDiamonds::drawCanvasWidget
getAlpha
| virtual uint8_t getAlpha | ( | ) | const |
Gets the current alpha value of the widget.
The alpha value is in range 255 (solid) to 0 (invisible).
The current alpha value.
getMinimalRect
| virtual Rect getMinimalRect | ( | ) | const |
Gets minimal rectangle containing the shape drawn by this widget.
Default implementation returns the size of the entire widget, but this function should be overwritten in subclasses and return the minimal rectangle containing the shape. See classes such as Circle for example implementations.
The minimal rectangle containing the shape drawn.
Reimplemented by: touchgfx::AbstractShape::getMinimalRect, touchgfx::Circle::getMinimalRect, touchgfx::Line::getMinimalRect
getPainter
| const AbstractPainter * getPainter | ( | ) | const |
getSolidRect
| virtual Rect getSolidRect | ( | ) | const |
Gets the largest solid (non-transparent) rectangle.
Since canvas widgets typically do not have a solid rect, it is recommended to return an empty rectangle.
The largest solid (non-transparent) rectangle.
Note
Function draw() might fail for some horizontal lines due to memory constraints. These lines will not be drawn and may cause strange display artifacts.
Reimplements: touchgfx::Drawable::getSolidRect
invalidate
| virtual void invalidate | ( | ) | const |
Invalidates the area covered by this CanvasWidget.
Since many widgets are a lot smaller than the actual size of the canvas widget, each widget must be able to tell the smallest rectangle completely containing the shape drawn by the widget. For example a circle arc is typically much smaller than the widget containing the circle.
Reimplements: touchgfx::Drawable::invalidate
setAlpha
| virtual void setAlpha | ( | uint8_t | newAlpha | ) | |
Sets the opacity (alpha value).
This can be used to fade it away by gradually decreasing the alpha value from 255 (solid) to 0 (invisible).
| newAlpha | The new alpha value. 255=solid, 0=invisible. |
Note
The user code must call invalidate() in order to update the display.
setPainter
| void setPainter | ( | const AbstractPainter & | painter | ) | |
Sets a painter for the CanvasWidget.
| painter | The painter for the CanvasWidget. |
Note
If setPainter() is used to change the painter to a different painter, the area containing the CanvasWidget is not automatically invalidated.
Protected Attributes Documentation
alpha
uint8_t alpha
The Alpha for this CanvasWidget.