3.1 屏幕尺寸(screen size)
屏幕大小是手机对角线的物理尺寸，单位是：英寸（inch），1 inch =2.54 cm（厘米）
image.png
3.2 屏幕分辨率(Resolution)
分辨率就是是指屏幕上垂直方向和水平方向上的像素个数，一般描述为：横像素 * 纵像素，如 720 * 1280,就是在纵方向上有1280个像素点，在横方向上有720个像素点。
image
日常所说的分辨率有两个概念，一个指显示器的分辨率，另一个指图像的分辨率。显示器分辨率指显示器所能显示的像素多少（720px*1280px），显示器可显示的像素越多，画面就越精细。图像分辨率则是单位英寸中所包含的像素点数，比如photoshop 里新建画布时设置的图像分辨率72ppi，其定义更趋近于分辨率本身的定义。
3.3 像素(pixel)
Pixels 我们看到屏幕上的图像由一个个像素组成，像素里包含色彩信息。如常说的手机分辨率：1080 x 1920 指的是手机宽度可展示1080像素，高度可展示1920像素。
image
3.4 ppi
ppi（Pixels Per Inch）即像素密度，指每英寸包含的物理像素的数量。ppi 是设备在物理上的属性值，取决于屏幕自身。设备的宽高都属于客观不可改变的值，所以 ppi 也是无法修改的，是硬件上一个客观存在无法改变的值。其计算公式如下：
image
3.5 dpi
dpi（Dots Per Inch）原先用于在印刷行业中描述每英寸包含有多少个点，在 Android 开发中则用来描述屏幕像素密度。屏幕像素密度决定了在软件概念上单位距离对应的像素总数，是手机在出厂时就会被写入系统配置文件中的一个属性值，一般情况下用户是无法修改该值的，但在开发者模式中有修改该值的入口，是软件上一个可以修改的值。
个人理解：dpi(dots per inch)、ppi(pixels per inch)，前者突出图像的打印像数密度，后者突出设备的像数密度。
image
3.6 dp/dip
density-independent pixels,dip是缩写，也可以更简单些称作dp。该单位的目的是屏蔽不同设备密度差异。
根据不同的屏幕分辨率，与px有不同的倍数关系。规定：1dp等于屏幕像素密度为160ppi时1px的长度，因此dp在整个系统大小是固定的。公式：1dp=（屏幕ppi/ 160）px。为简便起见，Android 将所有屏幕密度分组为六种通用密度，具体如下表：
image
3.7 sp
sp(Scaled Pixels)：通常用于指定字体的大小，当用户修改手机显示的字体时，字体大小会随之改变。
Android 自动适配屏幕方案—— smallestWidth
一、添加ScreenMatch 插件
image
二、dimens文件添加
添加一份dimens.xml文件作为适配的基准，文件内容主要声明尺寸
image
三、screenMatch生成values
image
代码
<?xml version="1.0" encoding="UTF-8"?>
<resources>
<!-- Your custom size defind by references, can be writted in anywhere, any module, any values/*.xml, for example: -->
<dimen name="common_margin">@dimen/dp_15</dimen>
<!-- dp and sp values, must be defind in this file! -->
<!-- view size,you can add if there is no one -->
<dimen name="dp_m_60">-60dp</dimen>
<dimen name="dp_m_30">-30dp</dimen>
<dimen name="dp_m_20">-20dp</dimen>
<dimen name="dp_m_12">-12dp</dimen>
<dimen name="dp_m_10">-10dp</dimen>
<dimen name="dp_m_8">-8dp</dimen>
<dimen name="dp_m_5">-5dp</dimen>
<dimen name="dp_m_4">-4dp</dimen>
<dimen name="dp_m_3">-3dp</dimen>
<dimen name="dp_m_3_5">-3.5dp</dimen>
<dimen name="dp_m_2">-2dp</dimen>
<dimen name="dp_m_1">-1dp</dimen>
<dimen name="dp_0">0dp</dimen>
<dimen name="dp_0_1">0.1dp</dimen>
<dimen name="dp_0_5">0.5dp</dimen>
<dimen name="dp_1">1dp</dimen>
<dimen name="dp_1_5">1.5dp</dimen>
<dimen name="dp_2">2dp</dimen>
<dimen name="dp_2_5">2.5dp</dimen>
<dimen name="dp_3">3dp</dimen>
<dimen name="dp_3_5">3.5dp</dimen>
<dimen name="dp_4">4dp</dimen>
<dimen name="dp_4_5">4.5dp</dimen>
<dimen name="dp_5">5dp</dimen>
<dimen name="dp_6">6dp</dimen>
<dimen name="dp_7">7dp</dimen>
<dimen name="dp_8">8dp</dimen>
<dimen name="dp_9">9dp</dimen>
<dimen name="dp_10">10dp</dimen>
<dimen name="dp_11">11dp</dimen>
<dimen name="dp_12">12dp</dimen>
<dimen name="dp_13">13dp</dimen>
<dimen name="dp_14">14dp</dimen>
<dimen name="dp_15">15dp</dimen>
<dimen name="dp_16">16dp</dimen>
<dimen name="dp_17">17dp</dimen>
<dimen name="dp_18">18dp</dimen>
<dimen name="dp_19">19dp</dimen>
<dimen name="dp_20">20dp</dimen>
<dimen name="dp_21">21dp</dimen>
<dimen name="dp_22">22dp</dimen>
<dimen name="dp_23">23dp</dimen>
<dimen name="dp_24">24dp</dimen>
<dimen name="dp_25">25dp</dimen>
<dimen name="dp_26">26dp</dimen>
<dimen name="dp_27">27dp</dimen>
<dimen name="dp_28">28dp</dimen>
<dimen name="dp_29">29dp</dimen>
<dimen name="dp_30">30dp</dimen>
<dimen name="dp_31">31dp</dimen>
<dimen name="dp_32">32dp</dimen>
<dimen name="dp_33">33dp</dimen>
<dimen name="dp_34">34dp</dimen>
<dimen name="dp_35">35dp</dimen>
<dimen name="dp_36">36dp</dimen>
<dimen name="dp_37">37dp</dimen>
<dimen name="dp_38">38dp</dimen>
<dimen name="dp_39">39dp</dimen>
<dimen name="dp_40">40dp</dimen>
<dimen name="dp_41">41dp</dimen>
<dimen name="dp_42">42dp</dimen>
<dimen name="dp_43">43dp</dimen>
<dimen name="dp_44">44dp</dimen>
<dimen name="dp_45">45dp</dimen>
<dimen name="dp_46">46dp</dimen>
<dimen name="dp_47">47dp</dimen>
<dimen name="dp_48">48dp</dimen>
<dimen name="dp_49">49dp</dimen>
<dimen name="dp_50">50dp</dimen>
<dimen name="dp_51">51dp</dimen>
<dimen name="dp_52">52dp</dimen>
<dimen name="dp_53">53dp</dimen>
<dimen name="dp_54">54dp</dimen>
<dimen name="dp_55">55dp</dimen>
<dimen name="dp_56">56dp</dimen>
<dimen name="dp_57">57dp</dimen>
<dimen name="dp_58">58dp</dimen>
<dimen name="dp_59">59dp</dimen>
<dimen name="dp_60">60dp</dimen>
<dimen name="dp_61">61dp</dimen>
<dimen name="dp_62">62dp</dimen>
<dimen name="dp_63">63dp</dimen>
<dimen name="dp_64">64dp</dimen>
<dimen name="dp_65">65dp</dimen>
<dimen name="dp_66">66dp</dimen>
<dimen name="dp_67">67dp</dimen>
<dimen name="dp_68">68dp</dimen>
<dimen name="dp_69">69dp</dimen>
<dimen name="dp_70">70dp</dimen>
<dimen name="dp_71">71dp</dimen>
<dimen name="dp_72">72dp</dimen>
<dimen name="dp_73">73dp</dimen>
<dimen name="dp_74">74dp</dimen>
<dimen name="dp_75">75dp</dimen>
<dimen name="dp_76">76dp</dimen>
<dimen name="dp_77">77dp</dimen>
<dimen name="dp_78">78dp</dimen>
<dimen name="dp_79">79dp</dimen>
<dimen name="dp_80">80dp</dimen>
<dimen name="dp_81">81dp</dimen>
<dimen name="dp_82">82dp</dimen>
<dimen name="dp_83">83dp</dimen>
<dimen name="dp_84">84dp</dimen>
<dimen name="dp_85">85dp</dimen>
<dimen name="dp_86">86dp</dimen>
<dimen name="dp_87">87dp</dimen>
<dimen name="dp_88">88dp</dimen>
<dimen name="dp_89">89dp</dimen>
<dimen name="dp_90">90dp</dimen>
<dimen name="dp_91">91dp</dimen>
<dimen name="dp_92">92dp</dimen>
<dimen name="dp_93">93dp</dimen>
<dimen name="dp_94">94dp</dimen>
<dimen name="dp_95">95dp</dimen>
<dimen name="dp_96">96dp</dimen>
<dimen name="dp_97">97dp</dimen>
<dimen name="dp_98">98dp</dimen>
<dimen name="dp_99">99dp</dimen>
<dimen name="dp_100">100dp</dimen>
<dimen name="dp_101">101dp</dimen>
<dimen name="dp_102">102dp</dimen>
<dimen name="dp_103">103dp</dimen>
<dimen name="dp_104">104dp</dimen>
<dimen name="dp_105">105dp</dimen>
<dimen name="dp_106">106dp</dimen>
<dimen name="dp_107">107dp</dimen>
<dimen name="dp_108">108dp</dimen>
<dimen name="dp_109">109dp</dimen>
<dimen name="dp_110">110dp</dimen>
<dimen name="dp_111">111dp</dimen>
<dimen name="dp_112">112dp</dimen>
<dimen name="dp_113">113dp</dimen>
<dimen name="dp_114">114dp</dimen>
<dimen name="dp_115">115dp</dimen>
<dimen name="dp_116">116dp</dimen>
<dimen name="dp_117">117dp</dimen>
<dimen name="dp_118">118dp</dimen>
<dimen name="dp_119">119dp</dimen>
<dimen name="dp_120">120dp</dimen>
<dimen name="dp_121">121dp</dimen>
<dimen name="dp_122">122dp</dimen>
<dimen name="dp_123">123dp</dimen>
<dimen name="dp_124">124dp</dimen>
<dimen name="dp_125">125dp</dimen>
<dimen name="dp_126">126dp</dimen>
<dimen name="dp_127">127dp</dimen>
<dimen name="dp_128">128dp</dimen>
<dimen name="dp_129">129dp</dimen>
<dimen name="dp_130">130dp</dimen>
<dimen name="dp_131">131dp</dimen>
<dimen name="dp_132">132dp</dimen>
<dimen name="dp_133">133dp</dimen>
<dimen name="dp_134">134dp</dimen>
<dimen name="dp_135">135dp</dimen>
<dimen name="dp_136">136dp</dimen>
<dimen name="dp_137">137dp</dimen>
<dimen name="dp_138">138dp</dimen>
<dimen name="dp_139">139dp</dimen>
<dimen name="dp_140">140dp</dimen>
<dimen name="dp_141">141dp</dimen>
<dimen name="dp_142">142dp</dimen>
<dimen name="dp_143">143dp</dimen>
<dimen name="dp_144">144dp</dimen>
<dimen name="dp_145">145dp</dimen>
<dimen name="dp_146">146dp</dimen>
<dimen name="dp_147">147dp</dimen>
<dimen name="dp_148">148dp</dimen>
<dimen name="dp_149">149dp</dimen>
<dimen name="dp_150">150dp</dimen>
<dimen name="dp_151">151dp</dimen>
<dimen name="dp_152">152dp</dimen>
<dimen name="dp_153">153dp</dimen>
<dimen name="dp_154">154dp</dimen>
<dimen name="dp_155">155dp</dimen>
<dimen name="dp_156">156dp</dimen>
<dimen name="dp_157">157dp</dimen>
<dimen name="dp_158">158dp</dimen>
<dimen name="dp_159">159dp</dimen>
<dimen name="dp_160">160dp</dimen>
<dimen name="dp_161">161dp</dimen>
<dimen name="dp_162">162dp</dimen>
<dimen name="dp_163">163dp</dimen>
<dimen name="dp_164">164dp</dimen>
<dimen name="dp_165">165dp</dimen>
<dimen name="dp_166">166dp</dimen>
<dimen name="dp_167">167dp</dimen>
<dimen name="dp_168">168dp</dimen>
<dimen name="dp_169">169dp</dimen>
<dimen name="dp_170">170dp</dimen>
<dimen name="dp_171">171dp</dimen>
<dimen name="dp_172">172dp</dimen>
<dimen name="dp_173">173dp</dimen>
<dimen name="dp_174">174dp</dimen>
<dimen name="dp_175">175dp</dimen>
<dimen name="dp_176">176dp</dimen>
<dimen name="dp_177">177dp</dimen>
<dimen name="dp_178">178dp</dimen>
<dimen name="dp_179">179dp</dimen>
<dimen name="dp_180">180dp</dimen>
<dimen name="dp_181">181dp</dimen>
<dimen name="dp_182">182dp</dimen>
<dimen name="dp_183">183dp</dimen>
<dimen name="dp_184">184dp</dimen>
<dimen name="dp_185">185dp</dimen>
<dimen name="dp_186">186dp</dimen>
<dimen name="dp_187">187dp</dimen>
<dimen name="dp_188">188dp</dimen>
<dimen name="dp_189">189dp</dimen>
<dimen name="dp_190">190dp</dimen>
<dimen name="dp_191">191dp</dimen>
<dimen name="dp_192">192dp</dimen>
<dimen name="dp_193">193dp</dimen>
<dimen name="dp_194">194dp</dimen>
<dimen name="dp_195">195dp</dimen>
<dimen name="dp_196">196dp</dimen>
<dimen name="dp_197">197dp</dimen>
<dimen name="dp_198">198dp</dimen>
<dimen name="dp_199">199dp</dimen>
<dimen name="dp_200">200dp</dimen>
<dimen name="dp_201">201dp</dimen>
<dimen name="dp_202">202dp</dimen>
<dimen name="dp_203">203dp</dimen>
<dimen name="dp_204">204dp</dimen>
<dimen name="dp_205">205dp</dimen>
<dimen name="dp_206">206dp</dimen>
<dimen name="dp_207">207dp</dimen>
<dimen name="dp_208">208dp</dimen>
<dimen name="dp_209">209dp</dimen>
<dimen name="dp_210">210dp</dimen>
<dimen name="dp_211">211dp</dimen>
<dimen name="dp_212">212dp</dimen>
<dimen name="dp_213">213dp</dimen>
<dimen name="dp_214">214dp</dimen>
<dimen name="dp_215">215dp</dimen>
<dimen name="dp_216">216dp</dimen>
<dimen name="dp_217">217dp</dimen>
<dimen name="dp_218">218dp</dimen>
<dimen name="dp_219">219dp</dimen>
<dimen name="dp_220">220dp</dimen>
<dimen name="dp_221">221dp</dimen>
<dimen name="dp_222">222dp</dimen>
<dimen name="dp_223">223dp</dimen>
<dimen name="dp_224">224dp</dimen>
<dimen name="dp_225">225dp</dimen>
<dimen name="dp_226">226dp</dimen>
<dimen name="dp_227">227dp</dimen>
<dimen name="dp_228">228dp</dimen>
<dimen name="dp_229">229dp</dimen>
<dimen name="dp_230">230dp</dimen>
<dimen name="dp_231">231dp</dimen>
<dimen name="dp_232">232dp</dimen>
<dimen name="dp_233">233dp</dimen>
<dimen name="dp_234">234dp</dimen>
<dimen name="dp_235">235dp</dimen>
<dimen name="dp_236">236dp</dimen>
<dimen name="dp_237">237dp</dimen>
<dimen name="dp_238">238dp</dimen>
<dimen name="dp_239">239dp</dimen>
<dimen name="dp_240">240dp</dimen>
<dimen name="dp_241">241dp</dimen>
<dimen name="dp_242">242dp</dimen>
<dimen name="dp_243">243dp</dimen>
<dimen name="dp_244">244dp</dimen>
<dimen name="dp_245">245dp</dimen>
<dimen name="dp_246">246dp</dimen>
<dimen name="dp_247">247dp</dimen>
<dimen name="dp_248">248dp</dimen>
<dimen name="dp_249">249dp</dimen>
<dimen name="dp_250">250dp</dimen>
<dimen name="dp_251">251dp</dimen>
<dimen name="dp_252">252dp</dimen>
<dimen name="dp_253">253dp</dimen>
<dimen name="dp_254">254dp</dimen>
<dimen name="dp_255">255dp</dimen>
<dimen name="dp_256">256dp</dimen>
<dimen name="dp_257">257dp</dimen>
<dimen name="dp_258">258dp</dimen>
<dimen name="dp_259">259dp</dimen>
<dimen name="dp_260">260dp</dimen>
<dimen name="dp_261">261dp</dimen>
<dimen name="dp_262">262dp</dimen>
<dimen name="dp_263">263dp</dimen>
<dimen name="dp_264">264dp</dimen>
<dimen name="dp_265">265dp</dimen>
<dimen name="dp_266">266dp</dimen>
<dimen name="dp_267">267dp</dimen>
<dimen name="dp_268">268dp</dimen>
<dimen name="dp_269">269dp</dimen>
<dimen name="dp_270">270dp</dimen>
<dimen name="dp_271">271dp</dimen>
<dimen name="dp_272">272dp</dimen>
<dimen name="dp_273">273dp</dimen>
<dimen name="dp_274">274dp</dimen>
<dimen name="dp_275">275dp</dimen>
<dimen name="dp_276">276dp</dimen>
<dimen name="dp_277">277dp</dimen>
<dimen name="dp_278">278dp</dimen>
<dimen name="dp_279">279dp</dimen>
<dimen name="dp_280">280dp</dimen>
<dimen name="dp_281">281dp</dimen>
<dimen name="dp_282">282dp</dimen>
<dimen name="dp_283">283dp</dimen>
<dimen name="dp_284">284dp</dimen>
<dimen name="dp_285">285dp</dimen>
<dimen name="dp_286">286dp</dimen>
<dimen name="dp_287">287dp</dimen>
<dimen name="dp_288">288dp</dimen>
<dimen name="dp_289">289dp</dimen>
<dimen name="dp_290">290dp</dimen>
<dimen name="dp_291">291dp</dimen>
<dimen name="dp_292">292dp</dimen>
<dimen name="dp_293">293dp</dimen>
<dimen name="dp_294">294dp</dimen>
<dimen name="dp_295">295dp</dimen>
<dimen name="dp_296">296dp</dimen>
<dimen name="dp_297">297dp</dimen>
<dimen name="dp_298">298dp</dimen>
<dimen name="dp_299">299dp</dimen>
<dimen name="dp_300">300dp</dimen>
<dimen name="dp_301">301dp</dimen>
<dimen name="dp_302">302dp</dimen>
<dimen name="dp_303">303dp</dimen>
<dimen name="dp_304">304dp</dimen>
<dimen name="dp_305">305dp</dimen>
<dimen name="dp_306">306dp</dimen>
<dimen name="dp_307">307dp</dimen>
<dimen name="dp_308">308dp</dimen>
<dimen name="dp_309">309dp</dimen>
<dimen name="dp_310">310dp</dimen>
<dimen name="dp_311">311dp</dimen>
<dimen name="dp_312">312dp</dimen>
<dimen name="dp_313">313dp</dimen>
<dimen name="dp_314">314dp</dimen>
<dimen name="dp_315">315dp</dimen>
<dimen name="dp_316">316dp</dimen>
<dimen name="dp_317">317dp</dimen>
<dimen name="dp_318">318dp</dimen>
<dimen name="dp_319">319dp</dimen>
<dimen name="dp_320">320dp</dimen>
<dimen name="dp_321">321dp</dimen>
<dimen name="dp_322">322dp</dimen>
<dimen name="dp_323">323dp</dimen>
<dimen name="dp_324">324dp</dimen>
<dimen name="dp_325">325dp</dimen>
<dimen name="dp_326">326dp</dimen>
<dimen name="dp_327">327dp</dimen>
<dimen name="dp_328">328dp</dimen>
<dimen name="dp_329">329dp</dimen>
<dimen name="dp_330">330dp</dimen>
<dimen name="dp_331">331dp</dimen>
<dimen name="dp_332">332dp</dimen>
<dimen name="dp_333">333dp</dimen>
<dimen name="dp_334">334dp</dimen>
<dimen name="dp_335">335dp</dimen>
<dimen name="dp_336">336dp</dimen>
<dimen name="dp_337">337dp</dimen>
<dimen name="dp_338">338dp</dimen>
<dimen name="dp_339">339dp</dimen>
<dimen name="dp_340">340dp</dimen>
<dimen name="dp_341">341dp</dimen>
<dimen name="dp_342">342dp</dimen>
<dimen name="dp_343">343dp</dimen>
<dimen name="dp_344">344dp</dimen>
<dimen name="dp_345">345dp</dimen>
<dimen name="dp_346">346dp</dimen>
<dimen name="dp_347">347dp</dimen>
<dimen name="dp_348">348dp</dimen>
<dimen name="dp_349">349dp</dimen>
<dimen name="dp_350">350dp</dimen>
<dimen name="dp_351">351dp</dimen>
<dimen name="dp_352">352dp</dimen>
<dimen name="dp_353">353dp</dimen>
<dimen name="dp_354">354dp</dimen>
<dimen name="dp_355">355dp</dimen>
<dimen name="dp_356">356dp</dimen>
<dimen name="dp_357">357dp</dimen>
<dimen name="dp_358">358dp</dimen>
<dimen name="dp_359">359dp</dimen>
<dimen name="dp_360">360dp</dimen>
<dimen name="dp_365">365dp</dimen>
<dimen name="dp_370">370dp</dimen>
<dimen name="dp_400">400dp</dimen>
<dimen name="dp_410">410dp</dimen>
<dimen name="dp_422">422dp</dimen>
<dimen name="dp_472">472dp</dimen>
<dimen name="dp_500">500dp</dimen>
<dimen name="dp_600">600dp</dimen>
<dimen name="dp_640">640dp</dimen>
<dimen name="dp_720">720dp</dimen>
<!-- font size,you can add if there is no one -->
<dimen name="sp_6">6sp</dimen>
<dimen name="sp_7">7sp</dimen>
<dimen name="sp_8">8sp</dimen>
<dimen name="sp_9">9sp</dimen>
<dimen name="sp_10">10sp</dimen>
<dimen name="sp_11">11sp</dimen>
<dimen name="sp_12">12sp</dimen>
<dimen name="sp_13">13sp</dimen>
<dimen name="sp_14">14sp</dimen>
<dimen name="sp_15">15sp</dimen>
<dimen name="sp_16">16sp</dimen>
<dimen name="sp_17">17sp</dimen>
<dimen name="sp_18">18sp</dimen>
<dimen name="sp_19">19sp</dimen>
<dimen name="sp_20">20sp</dimen>
<dimen name="sp_21">21sp</dimen>
<dimen name="sp_22">22sp</dimen>
<dimen name="sp_23">23sp</dimen>
<dimen name="sp_24">24sp</dimen>
<dimen name="sp_25">25sp</dimen>
<dimen name="sp_28">28sp</dimen>
<dimen name="sp_30">30sp</dimen>
<dimen name="sp_32">32sp</dimen>
<dimen name="sp_34">34sp</dimen>
<dimen name="sp_36">36sp</dimen>
<dimen name="sp_38">38sp</dimen>
<dimen name="sp_40">40sp</dimen>
<dimen name="sp_42">42sp</dimen>
<dimen name="sp_48">48sp</dimen>
</resources>
参考资料：Android 屏幕适配 - 林奋斗同学 - 博客园 (cnblogs.com)
Android 自动适配屏幕方案—— smallestWidth_android 自动适配大小屏幕-CSDN博客
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