win32限制改变窗口大小

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响应WM_SIZING消息，消息函数中做如下处理

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void CDemoDlg::OnSizing(UINT fwSide, LPRECT pRect)
{
	if (pRect->right - pRect->left < minWidth_)
	{
		if (fwSide == WMSZ_LEFT
			|| fwSide == WMSZ_TOPLEFT
			|| fwSide == WMSZ_BOTTOMLEFT)
		{
			pRect->left = pRect->right - minWidth_;
		}
		else
			pRect->right = pRect->left + minWidth_;
	}
	if (pRect->bottom - pRect->top < memHdcHeight_)
	{
		if (fwSide == WMSZ_TOP
			|| fwSide == WMSZ_TOPLEFT
			|| fwSide == WMSZ_TOPRIGHT)
		{
			pRect->top = pRect->bottom - minHeight_;
		}
		else
			pRect->bottom = pRect->top + minHeight_;
	}
 
	CDialogEx::OnSizing(fwSide, pRect);
}

如何让安卓APP第二次插上USB设备后不弹系统权限提示窗

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方法是把Android App做成随USB设备插入时自启动就可以了。
具体做法是在App的AndroidManifest.xml里，把要自启动activity的地方加两处USB_DEVICE_ATTACHED就可以了。

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        <activity
            android:name="com.serenegiant.usbcameratest2.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
                <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"/>            </intent-filter>
 
            <meta-data android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"                android:resource="@xml/device_filter"/>        </activity>

refer to: 梦幻贝壳, https://blog.csdn.net/menghuanbeike/article/details/78752715

Javascript技巧

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	<style style="display:block" contentEditable="true">
		body {
			background:rgb(255, 255, 255);
		}
	</style>
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const movies = {
	list: [
		{ title: 'Heat' },
		{ title: 'Interstellar' },
		{ title: 'Savior' }
	],
	[Symbol.iterator]() {
		let index = 0;
		return {
			next: () => {
				if (index < this.list.length) {
					const value = this.list[index++].title;
					return { value, done: false };
				}
				return { done: true };
			}
		};
	}
};
 
const [, secondMovieTitle = 'NonTitle'] = movies;
console.log(secondMovieTitle);
big = {
    foo: 'value Foo',
    bar: 'value Bar'
};
var { foo = 'Unk' } = big;
console.log(foo);
var { ['foo']: name = 'Unknown' } = big;
console.log(name);
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obj1 = {
	a() {
		console.log(this);
	},
	b: 'hi',
	c: () => {
		console.log(this);
	}
};
obj1.a();
obj1.c();
A1 = function() {
	console.log(this);
};
a1 = new A1;
A1();

Fall-back from the nopython compilation path to the object mode compilation

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出现此提示的原因是用@jit标注的函数内存在非数值运算语句。

比如下例中，time()函数和print()函数都不能出现在foo()函数中。正确写法为：

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import numba as nb
import time
 
@nb.jit
def foo(x, y):
	s = 0
	for i in range(x, y):
		s += i
	return s
 
tt = time.time()
print(foo(1, 100000000))
print('Time used: {} secs'.format(time.time() - tt))

本地的Documentation for Android SDK浏览还是太慢？

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在Android Studio中，通过SDK Manager将Documentation for Android SDK下载到本地后，在Android SDK目录下找到docs\index.html，在浏览器中打开，发现加载还是好慢，原因是本地网页又去访问互联网了。

想到的办法就是阻止浏览器访问外网，可参照

成为上帝玩转Chrome之指定阻止访问的网站

在此Chrome插件中加入以下阻止前缀字符串

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http://www.google.com/jsapi

就可在Chrome中极速查看安卓SDK文档了。

成为上帝玩转Chrome之指定阻止访问的网站

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在本地建一个目录，比如路径为d:\BlockSitePlugin

在此目录中写入以下四个文件：

manifest.json

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{
	"manifest_version":2,
	"name":"ChromeRequestBlocking",
	"version":"1.2.4",
	"author":"shengulong, euhat.com",
	"description":"Block url request.",
	"background":{"scripts":["background.js"]},
	"browser_action":{
		"default_popup":"popup.html",
		"default_title":"Block url request"
	},
	"permissions":[
		"storage",
		"unlimitedStorage",
		"webRequest",
		"webRequestBlocking",
		"<all_urls>"
	]
}
</all_urls>

Read more

美化输出xml或json

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xml

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from xml.dom.minidom import *
with open('d:/xml.txt', 'r') as f:
    print(parseString(f.read()).toprettyxml())

json

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python -m json.tool d:\json.txt

下载文件

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import requests
resp = requests.get('http://file.url', headers={'User-Agent':'Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36'})
with open("aa.dat", "wb") as f:
    f.write(resp.content)

android cmake命令行

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ninja这个工具是google的cmake特有的一个工具，不能用CMake官网下载安装的cmake编译安卓程序。

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set SDK_PATH=E:\euhat\android-sdk
set path=%SDK_PATH%\cmake\3.10.2.4988404\bin;%path%
 
cd app
mkdir manBuild
cd manBuild
 
cmake -DANDROID_ABI=armeabi-v7a -DANDROID_STL=c++_shared -DBUILD_SHARED_LIBS=ON -DCMAKE_C_FLAGS="-s" -DANDROID_PLATFORM=android-27 -DCMAKE_BUILD_TYPE=Debug -DANDROID_NDK=%SDK_PATH%\ndk-bundle -DCMAKE_TOOLCHAIN_FILE=%SDK_PATH%\ndk-bundle\build\cmake\android.toolchain.cmake -DCMAKE_GENERATOR=Ninja ..
 
ninja

refer to: https://bbs.csdn.net/topics/392257691?list=lz

在同一图里画两个隐函数图

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from sympy import *
x, y = symbols('x y')
p1 = plot_implicit(Eq(x**2 + y**2, 1), show = False, line_color = 'red')
p2 = plot_implicit(Eq(x + y, 1), show = False)
p1.extend(p2)
p1.show()

视频在微信手机端看不了

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比如用ffmpeg在电脑端录的mp4视频，拖到微信电脑端是可以看的，但打开微信手机端就不动了，只能看到第一帧。

解决办法是先将mp4格式转为mpg格式，再将mpg格式转为mp4格式，最后得到的mp4就可在微信手机端播放了：

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ffmpeg.exe -i old.mp4 temp.mpg
ffmpeg.exe -i temp.mpg new.mp4

附ffmpeg在windows下录屏方法：

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ffmpeg -f gdigrab -framerate 30 -offset_x 655 -offset_y 517 -video_size 511x374 -i desktop capture.mpg

ffmpeg在ubuntu下录屏方法：

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ffmpeg -framerate 25 -f x11grab -s 800x600 -i :0.0+100,200 capture.mp4

转码为mp4的方法：

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ffmpeg.exe -ss 5 -sseof 5 -i %1 -vf scale=-2:600 -y output.mp4
 
rem ffmpeg.exe -ss 5 -sseof 5 -i %1 -vf "pad=ceil(iw/2)*2:ceil(ih/2)*2" output.mp4

refer to:
https://github.com/GyanD/codexffmpeg/releases/tag/2021-12-02-git-4a6aece703
https://www.xzcblog.com/post-173.html