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c# - 使用 GraphicsPath 正确绘制文本

转载 作者:行者123 更新时间:2023-11-30 20:15:41 26 4
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如下图所示,PictureBox 中的文本与 TextBox 中的文本不同。如果我使用 Graphics.DrawString() 它工作正常,但是当我使用图形路径时,它会截断并且不显示整个文本。您认为我的代码有什么问题?

enter image description here

这是我的代码:

public LayerClass DrawString(LayerClass.Type _text, string text, RectangleF rect, Font _fontStyle, PaintEventArgs e)
{
using (StringFormat string_format = new StringFormat())
{
rect.Size = e.Graphics.MeasureString(text, _fontStyle);
rect.Location = new PointF(Shape.center.X - (rect.Width / 2), Shape.center.Y - (rect.Height / 2));
if(isOutlinedOrSolid)
{
using (GraphicsPath path = new GraphicsPath())
{
path.AddString(text, _fontStyle.FontFamily, (int)_fontStyle.Style, rect.Size.Height, rect, string_format);
e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
e.Graphics.CompositingQuality = CompositingQuality.HighQuality;
e.Graphics.CompositingMode = CompositingMode.SourceOver;
e.Graphics.DrawPath(new Pen(Color.Red, 1), path);
}
}
else
{
e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
e.Graphics.CompositingQuality = CompositingQuality.HighQuality;
e.Graphics.CompositingMode = CompositingMode.SourceOver;
e.Graphics.DrawString(text,_fontStyle,Brushes.Red, rect.Location);
}
}

this._Text = text;
this._TextRect = rect;
return new LayerClass(_text, this, text, rect);
}

最佳答案

GraphicsPath类以不同的方式计算文本对象的大小(如评论中所述)。文本大小是使用 Ems 边界矩形大小计算的。
Em 是一种独立于目标设备上下文的打印度量。
它指的是字体最宽的字母所占据的矩形,通常是字母“M”(发音为 em)。

目标 Em 大小可以用两种不同的方式计算:一种包括 Font descent,另一种不包括它。

float EMSize = (Font.SizeInPoints * [FontFamily].GetCellAscent([FontStyle]) 
/ [FontFamily].GetEmHeight([FontStyle])

float EMSize = (Font.SizeInPoints * 
([FontFamily].GetCellAscent([FontStyle] +
[FontFamily.GetCellDescent([FontStyle])) /
[FontFamily].GetEmHeight([FontStyle])

查看有关以下内容的文档:
FontFamily.GetEmHeight , FontFamily.GetCellAscentFontFamily.GetCellDescent

我在这里插入您可以在文档中找到的图。

Font Ascent-Descent

引用此处包含的一般信息:
Using Font and Text (MSDN)

本文档报告了有关如何转换点、像素和 Ems 的细节:
How to: Obtain Font Metrics (MSDN)


我假设您已经有一个包含/引用来自 UI 控件的字体设置和所需调整的类对象。
我在这里添加一个,其中包含一些属性,这些属性包含与问题相关的这些设置的子集。

此类根据用户选择的字体大小执行一些计算。
字体大小通常以磅为单位引用。然后使用当前屏幕 DPI 分辨率(或从像素维度转换为点),将此度量转换为像素。每个度量也转换为 Ems,如果您必须使用 GraphicsPath 绘制文本,这会派上用场。

Ems 大小的计算同时考虑了字体的AscentDescent
GraphicsPath 类在这种度量下效果更好,因为混合文本可以包含两个部分,如果没有,则该部分为 = 0

要计算使用特定字体和字体大小绘制的文本的容器框,请使用 GraphicsPath.GetBounds()方法:
([Canvas] 是提供 Paint 事件的 e.Graphics 对象的控件)

using (var path = new GraphicsPath())
using (var format = new StringFormat(StringFormatFlags.NoClip | StringFormatFlags.NoWrap))
{
format.Alignment = [StringAlignment.Center/Near/Far]; //As selected
format.LineAlignment = [StringAlignment.Center/Near/Far]; //As selected
//Add the Text to the GraphicsPath
path.AddString(fontObject.Text, fontObject.FontFamily,
(int)fontObject.FontStyle, fontObject.SizeInEms,
[Canvas].ClientRectangle, format);
//Ems size (bounding rectangle)
RectangleF textBounds = path.GetBounds(null, fontObject.Outline);
//Location of the Text
fontObject.Location = textBounds.Location;
}

[Canvas] 设备上下文中绘制文本:

private void Canvas_Paint(object sender, PaintEventArgs e)
{
using (var path = new GraphicsPath())
using (var format = new StringFormat(StringFormatFlags.NoClip | StringFormatFlags.NoWrap))
{
format.Alignment = [StringAlignment.Center/Near/Far]; //As selected
format.LineAlignment = [StringAlignment.Center/Near/Far]; //As selected

path.AddString(fontObject.Text, fontObject.FontFamily, (int)fontObject.FontStyle, fontObject.SizeInEms, Canvas.ClientRectangle, format);

e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
// When text is rendered directly
e.Graphics.TextRenderingHint = TextRenderingHint.ClearTypeGridFit;
// The composition properties are useful when drawing on a composited surface
// It has no effect when drawing on a Control's plain surface
e.Graphics.CompositingMode = CompositingMode.SourceOver;
e.Graphics.CompositingQuality = CompositingQuality.HighQuality;

if (fontObject.Outlined) {
e.Graphics.DrawPath(fontObject.Outline, path);
}
using(var brush = new SolidBrush(fontObject.FillColor)) {
e.Graphics.FillPath(brush, path);
}
}
}

使用该类及相关方法的视觉效果:

Font Outline Example

类对象,用作引用:

public class FontObject
{
private float currentScreenDPI = 0.0F;
private float m_SizeInPoints = 0.0F;
private float m_SizeInPixels = 0.0F;
public FontObject()
: this(string.Empty, FontFamily.GenericSansSerif, FontStyle.Regular, 18F) { }
public FontObject(string text, Font font)
: this(text, font.FontFamily, font.Style, font.SizeInPoints) { }
public FontObject(string text, FontFamily fontFamily, FontStyle fontStyle, float FontSize)
{
if (FontSize < 3) FontSize = 3;
using (Graphics g = Graphics.FromHwndInternal(IntPtr.Zero)) {
currentScreenDPI = g.DpiY;
}
Text = text;
FontFamily = fontFamily;
SizeInPoints = FontSize;
FillColor = Color.Black;
Outline = new Pen(Color.Black, 1);
Outlined = false;
}

public string Text { get; set; }
public FontStyle FontStyle { get; set; }
public FontFamily FontFamily { get; set; }
public Color FillColor { get; set; }
public Pen Outline { get; set; }
public bool Outlined { get; set; }
public float SizeInPoints {
get => m_SizeInPoints;
set { m_SizeInPoints = value;
m_SizeInPixels = (value * 72F) / currentScreenDPI;
SizeInEms = GetEmSize();
}
}
public float SizeInPixels {
get => m_SizeInPixels;
set { m_SizeInPixels = value;
m_SizeInPoints = (value * currentScreenDPI) / 72F;
SizeInEms = GetEmSize();
}
}

public float SizeInEms { get; private set; }
public PointF Location { get; set; }
public RectangleF DrawingBox { get; set; }

private float GetEmSize()
{
return (m_SizeInPoints *
(FontFamily.GetCellAscent(FontStyle) +
FontFamily.GetCellDescent(FontStyle))) /
FontFamily.GetEmHeight(FontStyle);
}
}

带有字体系列的组合框
创建自定义 ComboBox 并设置其 DrawMode = OwnerDrawVariable:

string[] fontList = FontFamily.Families.Where(f => f.IsStyleAvailable(FontStyle.Regular)).Select(f => f.Name).ToArray();

cboFontFamily.DrawMode = DrawMode.OwnerDrawVariable;
cboFontFamily.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
cboFontFamily.AutoCompleteSource = AutoCompleteSource.CustomSource;
cboFontFamily.AutoCompleteCustomSource.AddRange(fontList);
cboFontFamily.DisplayMember = "Name";
cboFontFamily.Items.AddRange(fontList);
cboFontFamily.Text = "Arial";

事件处理器:

private void cboFontFamily_DrawItem(object sender, DrawItemEventArgs e)
{
if ((cboFontFamily.Items.Count == 0) || e.Index < 0) return;
e.DrawBackground();

var flags = TextFormatFlags.Left | TextFormatFlags.VerticalCenter;
using (var family = new FontFamily(cboFontFamily.GetItemText(cboFontFamily.Items[e.Index])))
using (var font = new Font(family, 10F, FontStyle.Regular, GraphicsUnit.Point)) {
TextRenderer.DrawText(e.Graphics, family.Name, font, e.Bounds, cboFontFamily.ForeColor, flags);
}
e.DrawFocusRectangle();
}

private void cboFontFamily_MeasureItem(object sender, MeasureItemEventArgs e)
{
e.ItemHeight = (int)this.Font.Height + 4;
}

private void cboFontFamily_SelectionChangeCommitted(object sender, EventArgs e)
{
fontObject.FontFamily = new FontFamily(cboFontFamily.GetItemText(cboFontFamily.SelectedItem));
Canvas.Invalidate();
}

关于c# - 使用 GraphicsPath 正确绘制文本,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53060627/

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