MeasureString始终认为空格适合 [英] MeasureString always thinks whitespace will fit
问题描述
我正在尝试对字符串进行命中测试(我想从x偏移量获取char索引)，但是我遇到了度量字符串的问题.
I'm trying to do some hit testing on strings (I want to get the char index from the x offset), but I'm hitting issues with measure string.
这实际上是我正在使用的代码
This is essentially the code I am using
StringFormat sf = new StringFormat(StringFormatFlags.MeasureTrailingSpaces | StringFormatFlags.NoWrap | StringFormatFlags.LineLimit);
e.Graphics.MeasureString("test string", this.Font, new SizeF(xHitTestPosition, this.Font.Height), sf, out charFitted, out linesFilled);
应该将charFitted的值设置为它可以容纳的字符数(我根据尝试击中的点给它一个大小).
The value of charFitted should be set to the number of chars it could fit within the size its give (I'm giving it a size based on the point I am trying to hit test).
这很好，直到区域足够大以容纳测试"字符串为止.此时，charFitted从3("tes")跳到8("test").基本上，它总是包含所有空白，而不管它给定了多少空白.
This works fine until the area is large enough to hold the 'test' string. at this point charFitted jumps from 3 ('tes') to 8 ('test '). It basically always includes all the whitespace regardless of the space it has been give.
我尝试弄乱StringFormat设置，但似乎无济于事...
I've tried messing around with the StringFormat settings, but nothing seems t help...
我已包含一个演示以下内容的测试应用程序
I've included a test app bellow that demonstrates this
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
trackBar1.Maximum = this.ClientRectangle.Width;
}
protected override void OnPaint(PaintEventArgs e)
{
string sample = "abc def";
int charFitted, linesFilled;
e.Graphics.DrawString(sample, this.Font, Brushes.Black, PointF.Empty);
e.Graphics.DrawLine(Pens.Red, trackBar1.Value, 0, trackBar1.Value, 100);
StringFormat sf = new StringFormat(StringFormatFlags.MeasureTrailingSpaces | StringFormatFlags.NoWrap | StringFormatFlags.LineLimit);
sf.Trimming = StringTrimming.Character;
e.Graphics.MeasureString(sample, this.Font, new SizeF(trackBar1.Value, this.Font.Height), sf, out charFitted, out linesFilled);
textBox1.Text = "[" + sample.Substring(0, charFitted) + "]";
base.OnPaint(e);
}
private void trackBar1_Scroll(object sender, EventArgs e)
{
Invalidate();
}
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.trackBar1 = new System.Windows.Forms.TrackBar();
this.textBox1 = new System.Windows.Forms.TextBox();
((System.ComponentModel.ISupportInitialize)(this.trackBar1)).BeginInit();
this.SuspendLayout();
//
// trackBar1
//
this.trackBar1.Location = new System.Drawing.Point(13, 184);
this.trackBar1.Name = "trackBar1";
this.trackBar1.Size = new System.Drawing.Size(259, 45);
this.trackBar1.TabIndex = 0;
this.trackBar1.Scroll += new System.EventHandler(this.trackBar1_Scroll);
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(22, 229);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(237, 20);
this.textBox1.TabIndex = 1;
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(284, 261);
this.Controls.Add(this.textBox1);
this.Controls.Add(this.trackBar1);
this.Name = "Form1";
this.Text = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
((System.ComponentModel.ISupportInitialize)(this.trackBar1)).EndInit();
this.ResumeLayout(false);
this.PerformLayout();
}
#endregion
private System.Windows.Forms.TrackBar trackBar1;
private System.Windows.Forms.TextBox textBox1;
}
}
推荐答案
问题是"abc"和"abc"的长度相同.由于您没有打印出尾随空格，因此图形表示是相同的. 我会在末尾添加一个字符，然后测量字符串并删除添加的字符的长度.
The problem is that the length of "abc" and "abc " are the same. Since you don't print out the trailing spaces the graphical representation is the same. I would add a character at the end and then measure the string and remove the length of the added character.
将此与您的OnPaint一起使用，看来可行:
Swith your OnPaint to this and it seems to work:
protected override void OnPaint(PaintEventArgs e) {
string sample = "abc def";
e.Graphics.DrawString(sample, this.Font, Brushes.Black, PointF.Empty);
e.Graphics.DrawLine(Pens.Red, trackBar1.Value, 0, trackBar1.Value, 100);
StringFormat sf = new StringFormat(StringFormatFlags.MeasureTrailingSpaces | StringFormatFlags.NoWrap | StringFormatFlags.LineLimit);
sf.Trimming = StringTrimming.Character;
var underscoreWidth = e.Graphics.MeasureString("_", this.Font).Width;
for (int i = 0; i < sample.Length; i++) {
var s = sample.Substring(0, i + 1) + "_";
var size = e.Graphics.MeasureString(s, this.Font).Width - underscoreWidth;
if (size > trackBar1.Value) {
if (s.Length > 0) {
var ok = s.Substring(0, s.Length - 2);
textBox1.Text = "[" + ok + "]";
base.OnPaint(e);
return;
}
}
}
textBox1.Text = "[" + sample + "]";
base.OnPaint(e);
}
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