326 lines
10 KiB
C
326 lines
10 KiB
C
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/*=========================================================================
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Program: Visualization Toolkit
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Module: vtkTextRenderer.h
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Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
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All rights reserved.
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See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
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This software is distributed WITHOUT ANY WARRANTY; without even
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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PURPOSE. See the above copyright notice for more information.
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=========================================================================*/
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/**
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* @class vtkTextRenderer
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* @brief Interface for generating images and path data from
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* string data, using multiple backends.
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*
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*
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* vtkTextRenderer produces images, bounding boxes, and vtkPath
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* objects that represent text. The advantage of using this class is to easily
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* integrate mathematical expressions into renderings by automatically switching
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* between FreeType and MathText backends. If the input string contains at least
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* two "$" symbols separated by text, the MathText backend will be used.
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* Alternatively, the presence of unescaped "|" symbols defines multicolumn lines,
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* which are processed with the MathText backend.
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*
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* If the string does not meet these criteria, or if no MathText implementation is
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* available, the faster FreeType rendering facilities are used. Literal $
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* symbols can be used by escaping them with backslashes, "\$" (or "\\$" if the
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* string is set programmatically).
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*
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* For example, "Acceleration ($\\frac{m}{s^2}$)" will use MathText, but
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* "\\$500, \\$100" will use FreeType.
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*
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* By default, the backend is set to Detect, which determines the backend based
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* on the contents of the string. This can be changed by setting the
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* DefaultBackend ivar.
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*
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* Note that this class is abstract -- link to the vtkRenderingFreetype module
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* to get the default implementation.
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*/
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#ifndef vtkTextRenderer_h
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#define vtkTextRenderer_h
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#include "vtkObject.h"
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#include "vtkRenderingCoreModule.h" // For export macro
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#include "vtkTuple.h" // For metrics struct
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#include "vtkVector.h" // For metrics struct
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class vtkImageData;
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class vtkPath;
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class vtkStdString;
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class vtkTextProperty;
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namespace vtksys
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{
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class RegularExpression;
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}
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class VTKRENDERINGCORE_EXPORT vtkTextRendererCleanup
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{
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public:
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vtkTextRendererCleanup();
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~vtkTextRendererCleanup();
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private:
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vtkTextRendererCleanup(const vtkTextRendererCleanup& other) = delete;
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vtkTextRendererCleanup& operator=(const vtkTextRendererCleanup& rhs) = delete;
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};
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class VTKRENDERINGCORE_EXPORT vtkTextRenderer : public vtkObject
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{
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public:
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struct Metrics
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{
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/**
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* Construct a Metrics object with all members initialized to 0.
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*/
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Metrics()
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: BoundingBox(0)
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, TopLeft(0)
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, TopRight(0)
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, BottomLeft(0)
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, BottomRight(0)
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, Ascent(0)
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, Descent(0)
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{
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}
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/**
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* The axis-aligned bounding box of the rendered text and background, in
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* pixels. The origin of the bounding box is the anchor point of the data
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* when considering justification. Layout is { xMin, xMax, yMin, yMax }.
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*/
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vtkTuple<int, 4> BoundingBox;
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///@{
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/**
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* The corners of the rendered text (or background, if applicable), in pixels.
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* Uses the same origin as BoundingBox.
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*/
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vtkVector2i TopLeft;
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vtkVector2i TopRight;
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vtkVector2i BottomLeft;
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vtkVector2i BottomRight;
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///@}
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/**
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* Vectors representing the rotated ascent and descent of the text. This is
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* the distance above or below the baseline. Not all backends support this,
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* and may leave these vectors set to 0.
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* @{
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*/
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vtkVector2i Ascent;
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vtkVector2i Descent;
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/**@}*/
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};
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vtkTypeMacro(vtkTextRenderer, vtkObject);
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void PrintSelf(ostream& os, vtkIndent indent) override;
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/**
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* This is a singleton pattern New. There will be only ONE reference
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* to a vtkTextRenderer subclass object per process. Clients that
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* call this method must use Delete() on the object so that reference
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* counting will work. The single instance will be unreferenced when
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* the program exits. You should just use the static GetInstance() method
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* anyway to get the singleton. This method may return NULL if the object
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* factory cannot find an override.
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*/
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static vtkTextRenderer* New();
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/**
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* Return the singleton instance with no reference counting. May return NULL
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* if the object factory cannot find an override.
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*/
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static vtkTextRenderer* GetInstance();
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/**
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* Available backends. FreeType and MathText are provided in the default
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* implementation of this interface. Enum values less than 16 are reserved.
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* Custom overrides should define other backends starting at 16.
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*/
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enum Backend
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{
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Default = -1,
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Detect = 0,
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FreeType,
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MathText,
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UserBackend = 16
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};
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///@{
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/**
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* The backend to use when none is specified. Default: Detect
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*/
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vtkSetMacro(DefaultBackend, int);
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vtkGetMacro(DefaultBackend, int);
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///@}
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///@{
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/**
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* Determine the appropriate back end needed to render the given string.
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*/
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virtual int DetectBackend(const vtkStdString& str);
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///@}
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/**
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* Test for availability of various backends
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*/
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virtual bool FreeTypeIsSupported() { return false; }
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virtual bool MathTextIsSupported() { return false; }
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///@{
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/**
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* Given a text property and a string, get the bounding box {xmin, xmax,
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* ymin, ymax} of the rendered string in pixels. The origin of the bounding
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* box is the anchor point described by the horizontal and vertical
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* justification text property variables.
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* Return true on success, false otherwise.
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*/
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bool GetBoundingBox(
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vtkTextProperty* tprop, const vtkStdString& str, int bbox[4], int dpi, int backend = Default)
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{
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return this->GetBoundingBoxInternal(tprop, str, bbox, dpi, backend);
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}
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///@}
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///@{
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/**
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* Given a text property and a string, get some metrics for the rendered
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* string.
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* Return true on success, false otherwise.
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*/
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bool GetMetrics(vtkTextProperty* tprop, const vtkStdString& str, Metrics& metrics, int dpi,
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int backend = Default)
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{
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return this->GetMetricsInternal(tprop, str, metrics, dpi, backend);
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}
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///@}
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///@{
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/**
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* Given a text property and a string, this function initializes the
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* vtkImageData *data and renders it in a vtkImageData.
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* Return true on success, false otherwise. If using the overload that
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* specifies "textDims", the array will be overwritten with the pixel width
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* and height defining a tight bounding box around the text in the image,
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* starting from the upper-right corner. This is used when rendering for a
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* texture on graphics hardware that requires texture image dimensions to be
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* a power of two; textDims can be used to determine the texture coordinates
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* needed to cleanly fit the text on the target.
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* The origin of the image's extents is aligned with the anchor point
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* described by the text property's vertical and horizontal justification
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* options.
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*/
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bool RenderString(vtkTextProperty* tprop, const vtkStdString& str, vtkImageData* data,
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int textDims[2], int dpi, int backend = Default)
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{
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return this->RenderStringInternal(tprop, str, data, textDims, dpi, backend);
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}
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///@}
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///@{
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/**
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* This function returns the font size (in points) and sets the size in @a
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* tprop that is required to fit the string in the target rectangle. The
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* computed font size will be set in @a tprop as well. If an error occurs,
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* this function will return -1.
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*/
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int GetConstrainedFontSize(const vtkStdString& str, vtkTextProperty* tprop, int targetWidth,
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int targetHeight, int dpi, int backend = Default)
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{
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return this->GetConstrainedFontSizeInternal(
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str, tprop, targetWidth, targetHeight, dpi, backend);
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}
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///@}
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///@{
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/**
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* Given a text property and a string, this function populates the vtkPath
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* path with the outline of the rendered string. The origin of the path
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* coordinates is aligned with the anchor point described by the text
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* property's horizontal and vertical justification options.
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* Return true on success, false otherwise.
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*/
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bool StringToPath(
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vtkTextProperty* tprop, const vtkStdString& str, vtkPath* path, int dpi, int backend = Default)
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{
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return this->StringToPathInternal(tprop, str, path, dpi, backend);
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}
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///@}
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/**
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* Set to true if the graphics implementation requires texture image dimensions
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* to be a power of two. Default is true, but this member will be set
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* appropriately by vtkOpenGLRenderWindow::OpenGLInitContext when GL is
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* inited.
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*/
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void SetScaleToPowerOfTwo(bool scale) { this->SetScaleToPowerOfTwoInternal(scale); }
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friend class vtkTextRendererCleanup;
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protected:
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vtkTextRenderer();
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~vtkTextRenderer() override;
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///@{
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/**
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* Virtual methods for concrete implementations of the public methods.
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*/
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virtual bool GetBoundingBoxInternal(
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vtkTextProperty* tprop, const vtkStdString& str, int bbox[4], int dpi, int backend) = 0;
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virtual bool GetMetricsInternal(
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vtkTextProperty* tprop, const vtkStdString& str, Metrics& metrics, int dpi, int backend) = 0;
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virtual bool RenderStringInternal(vtkTextProperty* tprop, const vtkStdString& str,
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vtkImageData* data, int textDims[2], int dpi, int backend) = 0;
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virtual int GetConstrainedFontSizeInternal(const vtkStdString& str, vtkTextProperty* tprop,
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int targetWidth, int targetHeight, int dpi, int backend) = 0;
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virtual bool StringToPathInternal(
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vtkTextProperty* tprop, const vtkStdString& str, vtkPath* path, int dpi, int backend) = 0;
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virtual void SetScaleToPowerOfTwoInternal(bool scale) = 0;
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///@}
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/**
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* Set the singleton instance. Call Delete() on the supplied
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* instance after setting it to fix the reference count.
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*/
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static void SetInstance(vtkTextRenderer* instance);
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///@{
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/**
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* The singleton instance and the singleton cleanup instance.
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*/
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static vtkTextRenderer* Instance;
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static vtkTextRendererCleanup Cleanup;
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///@}
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vtksys::RegularExpression* MathTextRegExp;
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vtksys::RegularExpression* MathTextRegExp2;
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vtksys::RegularExpression* MathTextRegExpColumn;
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///@{
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/**
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* Replace all instances of "\$" with "$".
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*/
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virtual void CleanUpFreeTypeEscapes(vtkStdString& str);
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///@}
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/**
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* The backend to use when none is specified. Default: Detect
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*/
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int DefaultBackend;
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private:
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vtkTextRenderer(const vtkTextRenderer&) = delete;
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void operator=(const vtkTextRenderer&) = delete;
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};
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#endif // vtkTextRenderer_h
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